The Collaborative International Dictionary of English v.0.48:

Need \Need\, v. i.
   To be wanted; to be necessary. --Chaucer.
   [1913 Webster]

         When we have done it, we have done all that is in our
         power, and all that needs.               --Locke.
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The Collaborative International Dictionary of English v.0.48:

Need \Need\, adv.
   Of necessity. See Needs. [Obs.] --Chaucer.
   [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Need \Need\ (n[=e]d), n. [OE. need, neod, nede, AS. ne['a]d,
   n[=y]d; akin to D. nood, G. not, noth, Icel. nau[eth]r, Sw. &
   Dan. n["o]d, Goth. nau[thorn]s.]
   1. A state that requires supply or relief; pressing occasion
      for something; necessity; urgent want.
      [1913 Webster]

            And the city had no need of the sun.  --Rev. xxi.
                                                  23.
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            I have no need to beg.                --Shak.
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            Be governed by your needs, not by your fancy. --Jer.
                                                  Taylor.
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   2. Want of the means of subsistence; poverty; indigence;
      destitution. --Chaucer.
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            Famine is in thy cheeks;
            Need and oppression starveth in thine eyes. --Shak.
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   3. That which is needful; anything necessary to be done;
      (pl.) necessary things; business. [Obs.] --Chaucer.
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   4. Situation of need; peril; danger. [Obs.] --Chaucer.
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   Syn: Exigency; emergency; strait; extremity; necessity;
        distress; destitution; poverty; indigence; want; penury.

   Usage: Need, Necessity. Necessity is stronger than need;
          it places us under positive compulsion. We are
          frequently under the necessity of going without that
          of which we stand very greatly in need. It is also
          with the corresponding adjectives; necessitous
          circumstances imply the direct pressure of suffering;
          needy circumstances, the want of aid or relief.
          [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Need \Need\ (n[=e]d), v. t. [imp. & p. p. Needed; p. pr. & vb.
   n. Needing.] [See Need, n. Cf. AS. n[=y]dan to force,
   Goth. nau[thorn]jan.]
   To be in want of; to have cause or occasion for; to lack; to
   require, as supply or relief.
   [1913 Webster]

         Other creatures all day long
         Rove idle, unemployed, and less need rest. --Milton.
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   Note: With another verb, need is used like an auxiliary,
         generally in a negative sentence expressing requirement
         or obligation, and in this use it undergoes no change
         of termination in the third person singular of the
         present tense. "And the lender need not fear he shall
         be injured." --Anacharsis (Trans. ).
         [1913 Webster]

WordNet (r) 3.0 (2006):

need
    n 1: a condition requiring relief; "she satisfied his need for
         affection"; "God has no need of men to accomplish His
         work"; "there is a demand for jobs" [syn: need, demand]
    2: anything that is necessary but lacking; "he had sufficient
       means to meet his simple needs"; "I tried to supply his
       wants" [syn: need, want]
    3: the psychological feature that arouses an organism to action
       toward a desired goal; the reason for the action; that which
       gives purpose and direction to behavior; "we did not
       understand his motivation"; "he acted with the best of
       motives" [syn: motivation, motive, need]
    4: a state of extreme poverty or destitution; "their indigence
       appalled him"; "a general state of need exists among the
       homeless" [syn: indigence, need, penury, pauperism,
       pauperization]
    v 1: require as useful, just, or proper; "It takes nerve to do
         what she did"; "success usually requires hard work"; "This
         job asks a lot of patience and skill"; "This position
         demands a lot of personal sacrifice"; "This dinner calls
         for a spectacular dessert"; "This intervention does not
         postulate a patient's consent" [syn: necessitate, ask,
         postulate, need, require, take, involve, call
         for, demand] [ant: eliminate, obviate, rid of]
    2: have need of; "This piano wants the attention of a competent
       tuner" [syn: want, need, require]
    3: have or feel a need for; "always needing friends and money"

Moby Thesaurus II by Grady Ward, 1.0:

169 Moby Thesaurus words for "need":
   absence, ardor, arrearage, ask, bare cupboard, bare necessities,
   bare subsistence, basic, be forced, be hurting for, be in for,
   be in want, be indicated, be necessary, be obliged, be pinched,
   be poor, beggarliness, beggary, break, call, call for,
   cannot do otherwise, cannot help but, charge, claim, clamor for,
   commitment, committal, concupiscence, constraint, covet, crave,
   cry for, cry out for, curiosity, dearth, defalcation, defect,
   defectiveness, deficiency, deficit, demand, demand for,
   deprivation, desideration, desideratum, desire, destitution,
   devoir, difficulty, discontinuity, distress, drive, drought, duty,
   eagerness, emergency, empty purse, essential, essentials, exact,
   exaction, exigency, extremity, famine, fancy, fantasy, fundamental,
   gap, go on welfare, grinding poverty, gripe,
   hand-to-mouth existence, hanker, have, have got to, have need to,
   have occasion for, have to, hiatus, homelessness, hope, horme,
   hunger, impecuniousness, imperfection, impoverishment,
   incompleteness, indigence, indispensable, insufficiency,
   intellectual curiosity, interval, lack, lacuna, libido, long,
   lust for learning, mendicancy, mind, miss, missing link,
   moneylessness, must, must item, necessaries, necessary,
   necessities, necessitousness, necessity, need for, need to,
   needfulness, neediness, needs must, occasion, omission, ought,
   outage, passion, paucity, pauperism, pauperization, penury, pinch,
   pine, pleasure, pleasure principle, poorness, poverty, prerequire,
   prerequirement, prerequisite, privation, require, requirement,
   requisite, requisition, right, run short of, scarcity,
   sexual desire, shortage, shortcoming, shortfall, should,
   sine qua non, starvation, starve, stress, take doing,
   the necessary, the needful, thirst, thirst for knowledge, trouble,
   ullage, urge, use, want, want doing, wantage, wanting, will,
   will and pleasure, wish, wish fulfillment, yearn