The Collaborative International Dictionary of English v.0.48:

Prime \Prime\, a. [F., fr. L. primus first, a superl.
   corresponding to the compar. prior former. See Prior, a.,
   Foremost, Former, and cf. Prim, a., Primary,
   Prince.]
   1. First in order of time; original; primeval; primitive;
      primary. "Prime forests." --Tennyson.
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            She was not the prime cause, but I myself. --Milton.
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   Note: In this sense the word is nearly superseded by
         primitive, except in the phrase prime cost.
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   2. First in rank, degree, dignity, authority, or importance;
      as, prime minister. "Prime virtues." --Dryden.
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   3. First in excellence; of highest quality; as, prime wheat;
      a prime quality of cloth.
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   4. Early; blooming; being in the first stage. [Poetic]
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            His starry helm, unbuckled, showed him prime
            In manhood where youth ended.         --Milton.
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   5. Lecherous; lustful; lewd. [Obs.] --Shak.
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   6. Marked or distinguished by a mark (') called a prime mark.

   Note: In this dictionary the same typographic mark is used to
         indicate a weak accent in headwords, and minutes of a
         degree in angle measurements.
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   7. (Math.)
      (a) Divisible by no number except itself or unity; as, 7
          is a prime number.
      (b) Having no common factor; -- used with to; as, 12 is
          prime to 25.
          [Webster 1913 Suppl.]

   Prime and ultimate ratio. (Math.). See Ultimate.

   Prime conductor. (Elec.) See under Conductor.

   Prime factor (Arith.), a factor which is a prime number.

   Prime figure (Geom.), a figure which can not be divided
      into any other figure more simple than itself, as a
      triangle, a pyramid, etc.

   Prime meridian (Astron.), the meridian from which longitude
      is reckoned, as the meridian of Greenwich or Washington.


   Prime minister, the responsible head of a ministry or
      executive government; applied particularly to that of
      England.

   Prime mover. (Mech.)
      (a) A natural agency applied by man to the production of
          power. Especially: Muscular force; the weight and
          motion of fluids, as water and air; heat obtained by
          chemical combination, and applied to produce changes
          in the volume and pressure of steam, air, or other
          fluids; and electricity, obtained by chemical action,
          and applied to produce alternation of magnetic force.
      (b) An engine, or machine, the object of which is to
          receive and modify force and motion as supplied by
          some natural source, and apply them to drive other
          machines; as a water wheel, a water-pressure engine, a
          steam engine, a hot-air engine, etc.
      (c) Fig.: The original or the most effective force in any
          undertaking or work; as, Clarkson was the prime mover
          in English antislavery agitation.

   Prime number (Arith.), a number which is exactly divisible
      by no number except itself or unity, as 5, 7, 11.

   Prime vertical (Astron.), the vertical circle which passes
      through the east and west points of the horizon.

   Prime-vertical dial, a dial in which the shadow is
      projected on the plane of the prime vertical.

   Prime-vertical transit instrument, a transit instrument the
      telescope of which revolves in the plane of the prime
      vertical, -- used for observing the transit of stars over
      this circle.
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The Collaborative International Dictionary of English v.0.48:

Prime \Prime\, n.
   1. The first part; the earliest stage; the beginning or
      opening, as of the day, the year, etc.; hence, the dawn;
      the spring. --Chaucer.
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            In the very prime of the world.       --Hooker.
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            Hope waits upon the flowery prime.    --Waller.
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   2. The spring of life; youth; hence, full health, strength,
      or beauty; perfection. "Cut off in their prime."
      --Eustace. "The prime of youth." --Dryden.
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   3. That which is first in quantity; the most excellent
      portion; the best part.
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            Give him always of the prime.         --Swift.
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   4. [F. prime, LL. prima (sc. hora). See Prime, a.] The
      morning; specifically (R. C. Ch.), the first canonical
      hour, succeeding to lauds.
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            Early and late it rung, at evening and at prime.
                                                  --Spenser.
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   Note: Originally, prime denoted the first quarter of the
         artificial day, reckoned from 6 a. m. to 6 p. m.
         Afterwards, it denoted the end of the first quarter,
         that is, 9 a. m. Specifically, it denoted the first
         canonical hour, as now. Chaucer uses it in all these
         senses, and also in the sense of def. 1, above.
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               They sleep till that it was pryme large.
                                                  --Chaucer.
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   5. (Fencing) The first of the chief guards.
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   6. (Chem.) Any number expressing the combining weight or
      equivalent of any particular element; -- so called because
      these numbers were respectively reduced to their lowest
      relative terms on the fixed standard of hydrogen as 1.
      [Obs. or Archaic]
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   7. (Arith.) A prime number. See under Prime, a.
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   8. An inch, as composed of twelve seconds in the duodecimal
      system; -- denoted by [']. See 2d Inch, n., 1.
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   Prime of the moon, the new moon at its first appearance.
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The Collaborative International Dictionary of English v.0.48:

Prime \Prime\, v. i.
   1. To be renewed, or as at first. [Obs.]
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            Night's bashful empress, though she often wane,
            As oft repeats her darkness, primes again.
                                                  --Quarles.
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   2. To serve as priming for the charge of a gun.
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   3. To work so that foaming occurs from too violent
      ebullition, which causes water to become mixed with, and
      be carried along with, the steam that is formed; -- said
      of a steam boiler.
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The Collaborative International Dictionary of English v.0.48:

Prime \Prime\, v. t. [imp. & p. p. Primed; p. pr. & vb. n.
   Priming.] [From Prime, a.]
   1. To apply priming to, as a musket or a cannon; to apply a
      primer to, as a metallic cartridge.
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   2. To lay the first color, coating, or preparation upon (a
      surface), as in painting; as, to prime a canvas, a wall.
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   3. To prepare; to make ready; to instruct beforehand; to
      post; to coach; as, to prime a witness; the boys are
      primed for mischief. [Colloq.] --Thackeray.
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   4. To trim or prune, as trees. [Obs. or Prov. Eng.]
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   5. (Math.) To mark with a prime mark.
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   To prime a pump, to charge a pump with water, in order to
      put it in working condition.
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WordNet (r) 3.0 (2006):

prime
    adj 1: first in rank or degree; "an architect of premier rank";
           "the prime minister" [syn: premier(a), prime(a)]
    2: used of the first or originating agent; "prime mover"
    3: of superior grade; "choice wines"; "prime beef"; "prize
       carnations"; "quality paper"; "select peaches" [syn:
       choice, prime(a), prize, quality, select]
    4: of or relating to or being an integer that cannot be factored
       into other integers; "prime number"
    5: being at the best stage of development; "our manhood's prime
       vigor"- Robert Browning [syn: prime, meridian]
    n 1: a number that has no factor but itself and 1 [syn: prime,
         prime quantity]
    2: the period of greatest prosperity or productivity [syn:
       flower, prime, peak, heyday, bloom, blossom,
       efflorescence, flush]
    3: the second canonical hour; about 6 a.m.
    4: the time of maturity when power and vigor are greatest [syn:
       prime, prime of life]
    v 1: insert a primer into (a gun, mine, or charge) preparatory
         to detonation or firing; "prime a cannon"; "prime a mine"
    2: cover with a primer; apply a primer to [syn: prime,
       ground, undercoat]
    3: fill with priming liquid; "prime a car engine"

Moby Thesaurus II by Grady Ward, 1.0:

466 Moby Thesaurus words for "prime":
   Eastertide, Mass, Maytime, abecedarian, aboriginal, acme,
   admirable, adolescence, adulthood, adultness, advise,
   age of consent, algorismic, algorithmic, aliquot, all-absorbing,
   alpha, ancestral, antecedent, antenatal, antepatriarchal, anterior,
   anticipatory, apply paint, apprise, arch, atavistic, aurora,
   autochthonous, banner, basic, bedaub, bedizen, bedtime prayer,
   begild, beginning, besmear, best, break of day, breaking-in, brief,
   brightening, brush on paint, budding, budtime, butter, calcimine,
   camp meeting, capital, cardinal, central, champion, chanticleer,
   charge, chief, choice, chosen, church, church service, ci-devant,
   coach, coat, cock, cockcrow, cocklight, color, complexion,
   compline, controlling, cover, crack of dawn, cram, cram with facts,
   cream, creative, crowning, dab, dandy, daub, dawn, dawning,
   day-peep, daybreak, daylight, dayspring, decimal, deep-dye,
   detonate, devotions, differential, digital, dip, discharge,
   distemper, divine service, dominant, double-dye, drill,
   driving age, drop, duty, dye, earlier, earliest, early, educate,
   eject, elder, elect, elemental, elementary, elite, emblazon,
   embryonic, enamel, engild, even, evening devotions, evensong,
   excellent, exceptional, excite, exercises, exponential,
   extraordinary, face, famous, fast-dye, fat, fell, fetal, figural,
   figurate, figurative, fine, finite, fire, fire off, first,
   first blush, first brightening, first glance, first impression,
   first inning, first lap, first move, first round, first sight,
   first stage, first step, first-class, first-rate, first-string,
   flower, flower of age, focal, for the best, fore, foregoing,
   forehand, foremost, formative, former, forward, foundational,
   fractional, fresco, front, frontal, full age, full bloom,
   full growth, fullgrownness, fundamental, galvanize, gambit,
   gestatory, get ready, get up steam, gild, glaze, gloss, grain,
   great, greatest, greenness, grown-upness, gun, gun for, handpicked,
   head, headmost, hegemonic, heyday, highest, hit, hue, humanoid,
   illuminate, imaginary, imbue, impair, impossible, in embryo,
   in its infancy, in the bud, inaugural, inceptive, inchoate,
   inchoative, incipient, incunabular, infant, infantile, infinite,
   inform, ingrain, initial, initiative, initiatory, instruct,
   integral, introductory, inventive, irrational, japan, juvenility,
   lacquer, lauds, lay on, lay on color, le premier pas, leading,
   legal age, legalis homo, let fly, let off, light, liturgy, load,
   logarithmic, logometric, magisterial, maiden, main, majority,
   make ready, manhood, manlihood, master, matchless, matins,
   mature age, maturity, meeting, morn, morning devotions, motivate,
   move, nascent, natal, negative, night song, none, nones, nonesuch,
   nonpareil, noteworthy, notify, novena, numeral, numerary,
   numerative, numeric, odd, office, older, opening move, optimal,
   optimum, ordinal, original, outstanding, overriding, overruling,
   paint, pair, paragon, paramount, parget, parturient, patriarchal,
   peak, peep of day, peerless, pelt, pepper, pick, pick off, picked,
   pigment, pinnacle, pioneer, pique, pistol, plug, positive,
   possible, postnatal, pot, potshoot, potshot, praise meeting,
   prayer, prayer meeting, prayers, preadamite, preceding, precurrent,
   predominant, preeminent, preexistent, preglacial, pregnant,
   prehistoric, prehuman, premier, prenatal, prepare, preponderant,
   prevailing, previous, pride, primal, primary, primavera,
   prime of life, prime song, primeval, primitive, primitiveness,
   primitivity, primogenial, primoprimitive, primordial, principal,
   prior, pristine, prize, procreative, protohistoric, protohuman,
   puberty, pubescence, public worship, queen, quicken, quintessence,
   quintessential, radical, ranking, rational, real, reciprocal,
   revival, revival meeting, riddle, ripe age, riper years,
   rudimental, rudimentary, ruling, seedtime, select, senior, service,
   set, sext, shade, shadow, shellac, shoot, shoot at, shoot down,
   slap on, slather, slop on paint, smear, smear on, snipe, sovereign,
   spread on, spread with, spring, springtide, springtime, stain,
   star, steam up, stellar, stimulate, stipple, strike,
   stuff with knowledge, submultiple, sunrise, sunup, supereminent,
   superior, superlative, supreme, surd, surpassing, take a potshot,
   tar, teach, tent meeting, the best, the best ever, the tops,
   the very best, tierce, tinct, tincture, tinge, tint, toga virilis,
   tone, top, topflight, torpedo, train, transcendental, tutor,
   undercoat, underived, undersong, unmatchable, unmatched,
   unparalleled, unsurpassed, uppermost, ur, varnish, very best,
   vesper, vespers, vestibule of Day, vigils, virility, warm up,
   warming-up, wash, watch meeting, watch night, watch-night service,
   whitewash, wind, wind up, womanhood, womanlihood, worthy,
   years of discretion, youth, youthfulness, zenith