The Collaborative International Dictionary of English v.0.48:

Staff \Staff\ (st[.a]f), n.; pl. Staves (st[=a]vz or
   st[aum]vz; 277) or Staffs (st[.a]fs) in senses 1-9,
   Staffs in senses 10, 11. [AS. staef a staff; akin to LG. &
   D. staf, OFries. stef, G. stab, Icel. stafr, Sw. staf, Dan.
   stav, Goth. stabs element, rudiment, Skr. sth[=a]pay to cause
   to stand, to place. See Stand, and cf. Stab, Stave, n.]
   1. A long piece of wood; a stick; the long handle of an
      instrument or weapon; a pole or stick, used for many
      purposes; as, a surveyor's staff; the staff of a spear or
      pike.
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            And he put the staves into the rings on the sides of
            the altar to bear it withal.          --Ex. xxxviii.
                                                  7.
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            With forks and staves the felon to pursue. --Dryden.
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   2. A stick carried in the hand for support or defense by a
      person walking; hence, a support; that which props or
      upholds. "Hooked staves." --Piers Plowman.
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            The boy was the very staff of my age. --Shak.
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            He spoke of it [beer] in "The Earnest Cry," and
            likewise in the "Scotch Drink," as one of the staffs
            of life which had been struck from the poor man's
            hand.                                 --Prof.
                                                  Wilson.
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   3. A pole, stick, or wand borne as an ensign of authority; a
      badge of office; as, a constable's staff.
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            Methought this staff, mine office badge in court,
            Was broke in twain.                   --Shak.
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            All his officers brake their staves; but at their
            return new staves were delivered unto them.
                                                  --Hayward.
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   4. A pole upon which a flag is supported and displayed.
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   5. The round of a ladder. [R.]
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            I ascended at one [ladder] of six hundred and
            thirty-nine staves.                   --Dr. J.
                                                  Campbell (E.
                                                  Brown's
                                                  Travels).
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   6. A series of verses so disposed that, when it is concluded,
      the same order begins again; a stanza; a stave.
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            Cowley found out that no kind of staff is proper for
            an heroic poem, as being all too lyrical. --Dryden.
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   7. (Mus.) The five lines and the spaces on which music is
      written; -- formerly called stave.
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   8. (Mech.) An arbor, as of a wheel or a pinion of a watch.
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   9. (Surg.) The grooved director for the gorget, or knife,
      used in cutting for stone in the bladder.
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   10. [From Staff, 3, a badge of office.] (Mil.) An
       establishment of officers in various departments attached
       to an army, to a section of an army, or to the commander
       of an army. The general's staff consists of those
       officers about his person who are employed in carrying
       his commands into execution. See ['E]tat Major.
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   11. Hence: A body of assistants serving to carry into effect
       the plans of a superintendent or manager; sometimes used
       for the entire group of employees of an enterprise,
       excluding the top management; as, the staff of a
       newspaper.
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   Jacob's staff (Surv.), a single straight rod or staff,
      pointed and iron-shod at the bottom, for penetrating the
      ground, and having a socket joint at the top, used,
      instead of a tripod, for supporting a compass.

   Staff angle (Arch.), a square rod of wood standing flush
      with the wall on each of its sides, at the external angles
      of plastering, to prevent their being damaged.

   The staff of life, bread. "Bread is the staff of life."
      --Swift.

   Staff tree (Bot.), any plant of the genus Celastrus,
      mostly climbing shrubs of the northern hemisphere. The
      American species (Celastrus scandens) is commonly called
      bittersweet. See 2d Bittersweet, 3
       (b) .

   To set up one's staff, To put up one's staff, To set
   down one's staff or To put down one's staff, to take up
      one's residence; to lodge. [Obs.]
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The Collaborative International Dictionary of English v.0.48:

Bittersweet \Bit"ter*sweet`\, a.
   Sweet and then bitter or bitter and then sweet; esp. sweet
   with a bitter after taste; hence (Fig.), pleasant but
   painful.
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The Collaborative International Dictionary of English v.0.48:

Bittersweet \Bit"ter*sweet`\, n.
   1. Anything which is bittersweet.
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   2. A kind of apple so called. --Gower.
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   3. (Bot.)
      (a) A climbing shrub, with oval coral-red berries
          (Solanum dulcamara); woody nightshade. The whole
          plant is poisonous, and has a taste at first sweetish
          and then bitter. The branches are the officinal
          dulcamara.
      (b) An American woody climber (Celastrus scandens),
          whose yellow capsules open late in autumn, and
          disclose the red aril which covers the seeds; -- also
          called Roxbury waxwork.
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WordNet (r) 3.0 (2006):

bittersweet
    adj 1: tinged with sadness; "a movie with a bittersweet ending"
    2: having a taste that is a mixture of bitterness and sweetness
       [syn: bittersweet, semisweet]
    n 1: poisonous perennial Old World vine having violet flowers
         and oval coral-red berries; widespread weed in North
         America [syn: bittersweet, bittersweet nightshade,
         climbing nightshade, deadly nightshade, poisonous
         nightshade, woody nightshade, Solanum dulcamara]
    2: twining shrub of North America having yellow capsules
       enclosing scarlet seeds [syn: bittersweet, American
       bittersweet, climbing bittersweet, false bittersweet,
       staff vine, waxwork, shrubby bittersweet, Celastrus
       scandens]