The Collaborative International Dictionary of English v.0.48:

Conceit \Con*ceit"\, n. [Through French, fr. L. conceptus a
   conceiving, conception, fr. concipere to conceive: cf. OF. p.
   p. nom. conciez conceived. See Conceive, and cf. Concept,
   Deceit.]
   1. That which is conceived, imagined, or formed in the mind;
      idea; thought; image; conception.
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            In laughing, there ever procedeth a conceit of
            somewhat ridiculous.                  --Bacon.
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            A man wise in his own conceit.        --Prov. xxvi.
                                                  12.
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   2. Faculty of conceiving ideas; mental faculty; apprehension;
      as, a man of quick conceit. [Obs.]
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            How often, alas! did her eyes say unto me that they
            loved! and yet I, not looking for such a matter, had
            not my conceit open to understand them. --Sir P.
                                                  Sidney.
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   3. Quickness of apprehension; active imagination; lively
      fancy.
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            His wit's as thick as Tewksbury mustard; there's
            more conceit in him than is in a mallet. --Shak.
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   4. A fanciful, odd, or extravagant notion; a quant fancy; an
      unnatural or affected conception; a witty thought or turn
      of expression; a fanciful device; a whim; a quip.
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            On his way to the gibbet, a freak took him in the
            head to go off with a conceit.        --L'Estrange.
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            Some to conceit alone their works confine,
            And glittering thoughts struck out at every line.
                                                  --Pope.
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            Tasso is full of conceits . . . which are not only
            below the dignity of heroic verse but contrary to
            its nature.                           --Dryden.
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   5. An overweening idea of one's self; vanity.
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            Plumed with conceit he calls aloud.   --Cotton.
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   6. Design; pattern. [Obs.] --Shak.
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   In conceit with, in accord with; agreeing or conforming.

   Out of conceit with, not having a favorable opinion of; not
      pleased with; as, a man is out of conceit with his dress.


   To put [one] out of conceit with, to make one indifferent
      to a thing, or in a degree displeased with it.
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The Collaborative International Dictionary of English v.0.48:

Conceit \Con*ceit"\, v. t.
   To conceive; to imagine. [Archaic]
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         The strong, by conceiting themselves weak, are therebly
         rendered as inactive . . . as if they really were so.
                                                  --South.
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         One of two bad ways you must conceit me,
         Either a coward or a flatterer.          --Shak.
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The Collaborative International Dictionary of English v.0.48:

Conceit \Con*ceit"\, v. i.
   To form an idea; to think. [Obs.]
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         Those whose . . . vulgar apprehensions conceit but low
         of matrimonial purposes.                 --Milton.
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WordNet (r) 3.0 (2006):

conceit
    n 1: feelings of excessive pride [syn: amour propre,
         conceit, self-love, vanity]
    2: an elaborate poetic image or a far-fetched comparison of very
       dissimilar things
    3: a witty or ingenious turn of phrase; "he could always come up
       with some inspired off-the-wall conceit"
    4: an artistic device or effect; "the architect's brilliant
       conceit was to build the house around the tree"
    5: the trait of being unduly vain and conceited; false pride
       [syn: conceit, conceitedness, vanity] [ant:
       humbleness, humility]

Moby Thesaurus II by Grady Ward, 1.0:

232 Moby Thesaurus words for "conceit":
   abstract thought, act of thought, affectation,
   aggressive self-confidence, amour propre, aphorism, apothegm,
   apprehension, arrogance, assume, assumption, assurance, attitude,
   bee, believe, bluster, boast, boastfulness, boasting, bombast,
   bon mot, boutade, brag, braggadocio, braggartism, bragging,
   brainstorm, brainwork, bravado, bright idea, bright thought,
   brilliant idea, bumptiousness, capriccio, caprice, cerebration,
   chestiness, climate of opinion, cockiness, cogitation,
   common belief, community sentiment, complacence, complacency,
   conceitedness, conceive, concept, conception, conceptualization,
   conclusion, consensus gentium, consequence, consideration,
   coxcombry, crack, crank, craze, crazy idea, creative thought,
   crotchet, dandyism, egoism, egotism, epigram, estimate, estimation,
   ethos, excogitation, expect, eye, face, facetiae, fad, fancy,
   fanfaronade, fantastic notion, fantasticism, fantasy, feeling,
   flash of wit, flight of fancy, flight of wit, flimflam,
   fool notion, foppery, foppishness, freak, freakish inspiration,
   fumes of fancy, gasconade, gasconism, gather, general belief, gibe,
   happy thought, harebrained idea, haughtiness, headwork,
   heavy thinking, heroics, humor, idea, ideation, image,
   imageless thought, imagination, imaginativeness, imagine,
   imagining, imago, immodesty, impression, independence,
   intellection, intellectual exercise, intellectual object,
   intellectualization, jactation, jactitation, judgment, kink,
   lights, maggot, megrim, memory-trace, mental act, mental image,
   mental impression, mental labor, mental process, mentation, mind,
   mot, mystique, narcissism, nasty crack, noesis, notion,
   observation, obtrusiveness, opinion, pardonable pride,
   passing fancy, perception, perkiness, persiflage,
   personal judgment, pertness, play of wit, pleasantry,
   point of view, pomposity, popular belief, position, posture,
   presumption, prevailing belief, pride, pridefulness, proudness,
   public belief, public opinion, puppyism, purse-pride, quip,
   quips and cranks, quirk, ratiocination, reaction, reasoning,
   recept, reckon, reflection, repartee, representation, retort,
   riposte, rodomontade, sally, scintillation, self-admiration,
   self-assertiveness, self-complacency, self-conceit,
   self-confidence, self-consequence, self-esteem, self-importance,
   self-love, self-reliance, self-respect, self-sufficiency,
   sentiment, side, sight, smart crack, smart saying, smugness,
   snappy comeback, stance, stiff-necked pride, stiff-neckedness,
   straight thinking, stroke of wit, stuffiness, suppose, supposition,
   swagger, swelled head, swelled-headedness, theory, think, thinking,
   thinking aloud, thinking out, thought, toy, turn of thought,
   vagary, vainglory, vainness, vanity, vaunt, vauntery, vaunting,
   view, way of thinking, whim, whim-wham, whimsy, wisecrack,
   witticism