The Collaborative International Dictionary of English v.0.48:

Fall \Fall\ (f[add]l), v. i. [imp. Fell (f[e^]l); p. p.
   Fallen (f[add]l"'n); p. pr. & vb. n. Falling.] [AS.
   feallan; akin to D. vallen, OS. & OHG. fallan, G. fallen,
   Icel. Falla, Sw. falla, Dan. falde, Lith. pulti, L. fallere
   to deceive, Gr. sfa`llein to cause to fall, Skr. sphal,
   sphul, to tremble. Cf. Fail, Fell, v. t., to cause to
   fall.]
   1. To Descend, either suddenly or gradually; particularly, to
      descend by the force of gravity; to drop; to sink; as, the
      apple falls; the tide falls; the mercury falls in the
      barometer.
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            I beheld Satan as lightning fall from heaven. --Luke
                                                  x. 18.
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   2. To cease to be erect; to take suddenly a recumbent
      posture; to become prostrate; to drop; as, a child totters
      and falls; a tree falls; a worshiper falls on his knees.
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            I fell at his feet to worship him.    --Rev. xix.
                                                  10.
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   3. To find a final outlet; to discharge its waters; to empty;
      -- with into; as, the river Rhone falls into the
      Mediterranean.
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   4. To become prostrate and dead; to die; especially, to die
      by violence, as in battle.
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            A thousand shall fall at thy side.    --Ps. xci. 7.
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            He rushed into the field, and, foremost fighting,
            fell.                                 --Byron.
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   5. To cease to be active or strong; to die away; to lose
      strength; to subside; to become less intense; as, the wind
      falls.
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   6. To issue forth into life; to be brought forth; -- said of
      the young of certain animals. --Shak.
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   7. To decline in power, glory, wealth, or importance; to
      become insignificant; to lose rank or position; to decline
      in weight, value, price etc.; to become less; as, the
      price falls; stocks fell two points.
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            I am a poor fallen man, unworthy now
            To be thy lord and master.            --Shak.
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            The greatness of these Irish lords suddenly fell and
            vanished.                             --Sir J.
                                                  Davies.
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   8. To be overthrown or captured; to be destroyed.
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            Heaven and earth will witness,
            If Rome must fall, that we are innocent. --Addison.
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   9. To descend in character or reputation; to become degraded;
      to sink into vice, error, or sin; to depart from the
      faith; to apostatize; to sin.
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            Let us labor therefore to enter into that rest, lest
            any man fall after the same example of unbelief.
                                                  --Heb. iv. 11.
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   10. To become insnared or embarrassed; to be entrapped; to be
       worse off than before; as, to fall into error; to fall
       into difficulties.
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   11. To assume a look of shame or disappointment; to become or
       appear dejected; -- said of the countenance.
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             Cain was very wroth, and his countenance fell.
                                                  --Gen. iv. 5.
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             I have observed of late thy looks are fallen.
                                                  --Addison.
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   12. To sink; to languish; to become feeble or faint; as, our
       spirits rise and fall with our fortunes.
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   13. To pass somewhat suddenly, and passively, into a new
       state of body or mind; to become; as, to fall asleep; to
       fall into a passion; to fall in love; to fall into
       temptation.
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   14. To happen; to to come to pass; to light; to befall; to
       issue; to terminate.
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             The Romans fell on this model by chance. --Swift.
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             Sit still, my daughter, until thou know how the
             matter will fall.                    --Ruth. iii.
                                                  18.
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             They do not make laws, they fall into customs. --H.
                                                  Spencer.
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   15. To come; to occur; to arrive.
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             The vernal equinox, which at the Nicene Council
             fell on the 21st of March, falls now [1694] about
             ten days sooner.                     --Holder.
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   16. To begin with haste, ardor, or vehemence; to rush or
       hurry; as, they fell to blows.
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             They now no longer doubted, but fell to work heart
             and soul.                            --Jowett
                                                  (Thucyd. ).
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   17. To pass or be transferred by chance, lot, distribution,
       inheritance, or otherwise; as, the estate fell to his
       brother; the kingdom fell into the hands of his rivals.
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   18. To belong or appertain.
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             If to her share some female errors fall,
             Look on her face, and you'll forget them all.
                                                  --Pope.
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   19. To be dropped or uttered carelessly; as, an unguarded
       expression fell from his lips; not a murmur fell from
       him.
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   To fall abroad of (Naut.), to strike against; -- applied to
      one vessel coming into collision with another.

   To fall among, to come among accidentally or unexpectedly.


   To fall astern (Naut.), to move or be driven backward; to
      be left behind; as, a ship falls astern by the force of a
      current, or when outsailed by another.

   To fall away.
       (a) To lose flesh; to become lean or emaciated; to pine.
       (b) To renounce or desert allegiance; to revolt or rebel.
       (c) To renounce or desert the faith; to apostatize.
           "These . . . for a while believe, and in time of
           temptation fall away." --Luke viii. 13.
       (d) To perish; to vanish; to be lost. "How . . . can the
           soul . . . fall away into nothing?" --Addison.
       (e) To decline gradually; to fade; to languish, or become
           faint. "One color falls away by just degrees, and
           another rises insensibly." --Addison.

   To fall back.
       (a) To recede or retreat; to give way.
       (b) To fail of performing a promise or purpose; not to
           fulfill.

   To fall back upon or To fall back on.
       (a) (Mil.) To retreat for safety to (a stronger position
           in the rear, as to a fort or a supporting body of
           troops).
       (b) To have recourse to (a reserved fund, a more reliable
           alternative, or some other available expedient or
           support).

   To fall calm, to cease to blow; to become calm.

   To fall down.
       (a) To prostrate one's self in worship. "All kings shall
           fall down before him." --Ps. lxxii. 11.
       (b) To sink; to come to the ground. "Down fell the
           beauteous youth." --Dryden.
       (c) To bend or bow, as a suppliant.
       (d) (Naut.) To sail or drift toward the mouth of a river
           or other outlet.

   To fall flat, to produce no response or result; to fail of
      the intended effect; as, his speech fell flat.

   To fall foul of.
       (a) (Naut.) To have a collision with; to become entangled
           with
       (b) To attack; to make an assault upon.

   To fall from, to recede or depart from; not to adhere to;
      as, to fall from an agreement or engagement; to fall from
      allegiance or duty.

   To fall from grace (M. E. Ch.), to sin; to withdraw from
      the faith.

   To fall home (Ship Carp.), to curve inward; -- said of the
      timbers or upper parts of a ship's side which are much
      within a perpendicular.

   To fall in.
       (a) To sink inwards; as, the roof fell in.
       (b) (Mil.) To take one's proper or assigned place in
           line; as, to fall in on the right.
       (c) To come to an end; to terminate; to lapse; as, on the
           death of Mr. B., the annuuity, which he had so long
           received, fell in.
       (d) To become operative. "The reversion, to which he had
           been nominated twenty years before, fell in."
           --Macaulay.

   To fall into one's hands, to pass, often suddenly or
      unexpectedly, into one's ownership or control; as, to
      spike cannon when they are likely to fall into the hands
      of the enemy.

   To fall in with.
       (a) To meet with accidentally; as, to fall in with a
           friend.
       (b) (Naut.) To meet, as a ship; also, to discover or come
           near, as land.
       (c) To concur with; to agree with; as, the measure falls
           in with popular opinion.
       (d) To comply; to yield to. "You will find it difficult
           to persuade learned men to fall in with your
           projects." --Addison.

   To fall off.
       (a) To drop; as, fruits fall off when ripe.
       (b) To withdraw; to separate; to become detached; as,
           friends fall off in adversity. "Love cools,
           friendship falls off, brothers divide." --Shak.
       (c) To perish; to die away; as, words fall off by disuse.
       (d) To apostatize; to forsake; to withdraw from the
           faith, or from allegiance or duty.
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                 Those captive tribes . . . fell off
                 From God to worship calves.      --Milton.
       (e) To forsake; to abandon; as, his customers fell off.
       (f) To depreciate; to change for the worse; to
           deteriorate; to become less valuable, abundant, or
           interesting; as, a falling off in the wheat crop; the
           magazine or the review falls off. "O Hamlet, what a
           falling off was there!" --Shak.
       (g) (Naut.) To deviate or trend to the leeward of the
           point to which the head of the ship was before
           directed; to fall to leeward.

   To fall on.
       (a) To meet with; to light upon; as, we have fallen on
           evil days.
       (b) To begin suddenly and eagerly. "Fall on, and try the
           appetite to eat." --Dryden.
       (c) To begin an attack; to assault; to assail. "Fall on,
           fall on, and hear him not." --Dryden.
       (d) To drop on; to descend on.

   To fall out.
       (a) To quarrel; to begin to contend.
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                 A soul exasperated in ills falls out
                 With everything, its friend, itself. --Addison.
       (b) To happen; to befall; to chance. "There fell out a
           bloody quarrel betwixt the frogs and the mice."
           --L'Estrange.
       (c) (Mil.) To leave the ranks, as a soldier.

   To fall over.
       (a) To revolt; to desert from one side to another.
       (b) To fall beyond. --Shak.

   To fall short, to be deficient; as, the corn falls short;
      they all fall short in duty.

   To fall through, to come to nothing; to fail; as, the
      engageent has fallen through.

   To fall to, to begin. "Fall to, with eager joy, on homely
      food." --Dryden.

   To fall under.
       (a) To come under, or within the limits of; to be
           subjected to; as, they fell under the jurisdiction of
           the emperor.
       (b) To come under; to become the subject of; as, this
           point did not fall under the cognizance or
           deliberations of the court; these things do not fall
           under human sight or observation.
       (c) To come within; to be ranged or reckoned with; to be
           subordinate to in the way of classification; as,
           these substances fall under a different class or
           order.

   To fall upon.
       (a) To attack. [See To fall on.]
       (b) To attempt; to have recourse to. "I do not intend to
           fall upon nice disquisitions." --Holder.
       (c) To rush against.
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   Note: Fall primarily denotes descending motion, either in a
         perpendicular or inclined direction, and, in most of
         its applications, implies, literally or figuratively,
         velocity, haste, suddenness, or violence. Its use is so
         various, and so mush diversified by modifying words,
         that it is not easy to enumerate its senses in all its
         applications.
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The Collaborative International Dictionary of English v.0.48:

Falling \Fall"ing\, a. & n.
   from Fall, v. i.
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   Falling away, Falling off, etc. See To fall away, To
      fall off, etc., under Fall, v. i.

   Falling band, the plain, broad, linen collar turning down
      over the doublet, worn in the early part of the 17th
      century.

   Falling sickness (Med.), epilepsy. --Shak.

   Falling star. (Astron.) See Shooting star.

   Falling stone, a stone falling through the atmosphere; a
      meteorite; an a["e]rolite.

   Falling tide, the ebb tide.

   Falling weather, a rainy season. [Colloq.] --Bartlett.
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WordNet (r) 3.0 (2006):

falling
    adj 1: decreasing in amount or degree; "falling temperature"
    2: becoming lower or less in degree or value; "a falling
       market"; "falling incomes" [ant: rising]
    3: coming down freely under the influence of gravity; "the eerie
       whistle of dropping bombs"; "falling rain" [syn: dropping,
       falling]

Moby Thesaurus II by Grady Ward, 1.0:

83 Moby Thesaurus words for "falling":
   cascading, collapsing, coming apart, cracking, crumbling, dangling,
   decadent, deciduous, declined, declining, declivate, declivitous,
   declivous, decurrent, degenerate, dependent, depending, descendant,
   descending, deteriorating, dipping, disintegrating, down,
   down-reaching, downcoming, downfalling, downgoing, downgrade,
   downhill, downsinking, downward, draining, drooping, dropping,
   dwindling, ebbing, effete, fading, failing, falling loosely,
   flagging, flowing, fragmenting, going to pieces, hanging, hung,
   languishing, marcescent, on the descendant, on the downgrade,
   pendent, pending, pendulant, pendular, penduline, pendulous,
   pensile, pining, plummeting, plunging, regressive, retrograde,
   retrogressive, sagging, setting, shriveling, sinking, sliding,
   slipping, slumping, submerging, subsiding, suspended, swinging,
   tabetic, tottering, tumbledown, waning, wasting, weeping, wilting,
   withering, worsening