The Collaborative International Dictionary of English v.0.48:

Compact \Com"pact\ (k[o^]m"p[a^]kt), n. [L. compactum, fr.
   compacisci, p. p. compactus, to make an agreement with; com-
   + pacisci to make an agreement. See Pact.]
   An agreement between parties; a covenant or contract.
   [1913 Webster]

         The law of nations depends on mutual compacts,
         treaties, leagues, etc.                  --Blackstone.
   [1913 Webster]

         Wedlock is described as the indissoluble compact.
                                                  --Macaulay.
   [1913 Webster]

         The federal constitution has been styled a compact
         between the States by which it was ratified. --Wharton.

   Syn: See Covenant.
        [1913 Webster] compact disc

The Collaborative International Dictionary of English v.0.48:

Compact \Com*pact"\, v. t. [imp. & p. p. Compacted; p. pr. &
   vb. n. Compacting.]
   1. To thrust, drive, or press closely together; to join
      firmly; to consolidate; to make close; -- as the parts
      which compose a body.
      [1913 Webster]

            Now the bright sun compacts the precious stone.
                                                  --Blackstone.
      [1913 Webster]

   2. To unite or connect firmly, as in a system.
      [1913 Webster]

            The whole body fitly joined together and compacted
            by that which every joint supplieth.  --Eph. iv. 16.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Compact \Com*pact"\ (k[o^]m*p[a^]kt"), p. p. & a. [L. compactus,
   p. p. of compingere to join or unite; com- + pangere to
   fasten, fix: cf. F. compacte. See Pact.]
   1. Joined or held together; leagued; confederated. [Obs.]
      "Compact with her that's gone." --Shak.
      [1913 Webster]

            A pipe of seven reeds, compact with wax together.
                                                  --Peacham.
      [1913 Webster]

   2. Composed or made; -- with of. [Poetic]
      [1913 Webster]

            A wandering fire,
            Compact of unctuous vapor.            --Milton.
      [1913 Webster]

   3. Closely or firmly united, as the particles of solid
      bodies; firm; close; solid; dense.
      [1913 Webster]

            Glass, crystal, gems, and other compact bodies.
                                                  --Sir I.
                                                  Newton.
      [1913 Webster]

   4. Brief; close; pithy; not diffuse; not verbose; as, a
      compact discourse.

   Syn: Firm; close; solid; dense; pithy; sententious.
        [1913 Webster]

WordNet (r) 3.0 (2006):

compact
    adj 1: closely and firmly united or packed together; "compact
           soil"; "compact clusters of flowers" [ant: loose]
    2: having a short and solid form or stature; "a wrestler of
       compact build"; "he was tall and heavyset"; "stocky legs"; "a
       thickset young man" [syn: compact, heavyset, stocky,
       thick, thickset]
    3: briefly giving the gist of something; "a short and
       compendious book"; "a compact style is brief and pithy";
       "succinct comparisons"; "a summary formulation of a wide-
       ranging subject" [syn: compendious, compact, succinct,
       summary]
    n 1: a small cosmetics case with a mirror; to be carried in a
         woman's purse [syn: compact, powder compact]
    2: a signed written agreement between two or more parties
       (nations) to perform some action [syn: covenant, compact,
       concordat]
    3: a small and economical car [syn: compact, compact car]
    v 1: have the property of being packable or of compacting
         easily; "This powder compacts easily"; "Such odd-shaped
         items do not pack well" [syn: compact, pack]
    2: compress into a wad; "wad paper into the box" [syn: pack,
       bundle, wad, compact]
    3: make more compact by or as if by pressing; "compress the
       data" [syn: compress, compact, pack together] [ant:
       decompress, uncompress]
    4: squeeze or press together; "she compressed her lips"; "the
       spasm contracted the muscle" [syn: compress, constrict,
       squeeze, compact, contract, press]

Moby Thesaurus II by Grady Ward, 1.0:

313 Moby Thesaurus words for "compact":
   Spartan, abbreviate, abbreviated, abridged, agree, agree to,
   agreement, airtight, ammunition box, aphoristic, aposiopestic, ark,
   attache case, baby, baby-sized, bandolier, bantam, banty, bargain,
   bargain for, base, billfold, bin, bond, boot, box, brief,
   briefcase, bristling, brusque, bunched, bunker, caisson, canister,
   capsula, capsule, cardcase, carton, casket, cedar chest, chest,
   cigarette case, circumscribe, cist, clamped, clipped, close,
   close-knit, close-textured, close-woven, clown white, coarct,
   coffer, coffin, coincident, cold cream, combine, compact,
   compacted, compendious, comprehensive, compress, compressed,
   concentrate, concentrated, concise, concrete, concurrent, condense,
   condensed, cone, congest, congested, conjoint, conjugate, conjunct,
   consolidate, consolidated, consortium, constrict, constricted,
   constringe, contract, contracted, convention,
   cordial understanding, corporate, cosmetics, covenant, cram,
   crammed, crammed full, cramp, cramped, crate, crawling, crib,
   crisp, crowd, crowded, curt, curtail, curtal, curtate, cut,
   decrease, decurtate, dense, densen, densify, diminutive,
   dispatch box, do a deal, docked, draw, draw in, draw together,
   drugstore complexion, duodecimo, dustproof, dusttight, elliptic,
   engage, entente, entente cordiale, envelope, epigrammatic, etui,
   eye shadow, eyebrow pencil, fast, file, file folder, filing box,
   firm, folio, foundation, foundation cream, full, gasproof,
   gastight, gluey, gnomic, greasepaint, hand cream, hand lotion,
   handy, hard, heavy, hermetic, hermetically sealed, holster,
   hope chest, housewife, hussy, hutch, impenetrable, impermeable,
   inclusive, instantaneous, integrate, jam, jam-packed, jammed,
   joined, joint, kit, knit, knitted, laconic, letter file,
   lightproof, lighttight, lip rouge, lipstick, little, low,
   make a deal, makeup, mascara, massive, meaty, miniature,
   miniaturized, minikin, minimal, minuscule, monstrance, mudpack,
   mutual understanding, nail polish, narrow, nipped, nonporous,
   oilproof, oiltight, ostensorium, packed, packet, packing case,
   pact, paint, pillbox, pinched, pinched-in, pithy, pocket,
   pocket-sized, pod, pointed, pony, populous, portfolio, powder,
   powder box, powder puff, press, promise, pruned, pucker, pucker up,
   puckered, puff, purse, pursed, quiver, rack, rainproof, raintight,
   ram down, reduce, reliquary, reserved, rouge, sarcophagus,
   scabbard, sealed, sententious, serried, set, sheath, short,
   short and sweet, shorten, shortened, shut fast, skippet, small,
   small-scale, smokeproof, smoketight, snuffbox, snug, socket, solid,
   solidified, solidify, spectacle case, squeeze, squeezed, staunch,
   stipulate, stormproof, stormtight, strangle, strangled,
   strangulate, strangulated, subminiature, substantial, succinct,
   summary, swarming, synopsized, synoptic, taciturn, talcum,
   talcum powder, tea chest, teeming, terse, thick, thick-growing,
   thickset, tight, till, tinderbox, to the point, toy, transaction,
   transient, truncated, twelvemo, understanding, undertake, unite,
   vanishing cream, vanity case, vasculum, vest-pocket, viscid,
   viscose, viscous, wallet, war paint, wasp-waisted, water-repellant,
   waterproof, watertight, windproof, windtight, wrinkle, wrinkled



The Jargon File (version 4.4.7, 29 Dec 2003):

compact
 adj.

    Of a design, describes the valuable property that it can all be apprehended
    at once in one's head. This generally means the thing created from the
    design can be used with greater facility and fewer errors than an
    equivalent tool that is not compact. Compactness does not imply triviality
    or lack of power; for example, C is compact and FORTRAN is not, but C is
    more powerful than FORTRAN. Designs become non-compact through accreting 
    features and cruft that don't merge cleanly into the overall design
    scheme (thus, some fans of Classic C maintain that ANSI C is no longer
    compact).


The Free On-line Dictionary of Computing (30 December 2018):

compact
finite
isolated

   1.  (Or "finite", "isolated") In domain theory, an
   element d of a cpo D is compact if and only if, for any
   chain S, a subset of D,

   	d <= lub S  =>  there exists s in S such that d <= s.

   I.e. you always reach d (or better) after a finite number of
   steps up the chain.

   ("<=" is written in LaTeX as \sqsubseteq).

   [Jargon File]

   (1995-01-13)

   2.  Of a design, describes the valuable property that
   it can all be apprehended at once in one's head.  This
   generally means the thing created from the design can be used
   with greater facility and fewer errors than an equivalent tool
   that is not compact.  Compactness does not imply triviality or
   lack of power; for example, C is compact and Fortran is
   not, but C is more powerful than Fortran.  Designs become
   non-compact through accreting features and cruft that
   don't merge cleanly into the overall design scheme (thus, some
   fans of Classic C maintain that ANSI C is no longer
   compact).

   (2008-10-13)


Bouvier's Law Dictionary, Revised 6th Ed (1856):

COMPACT, contracts. In its more general sense, it signifies an agreement. In
its strict sense, it imports a contract between parties, which creates
obligations and rights capable of being enforced, and contemplated as such
between the parties, in their distinct and independent characters. Story,
Const. B. 3, c. 3; Rutherf. Inst. B. 2, c. 6, Sec. 1. 2. The constitution of
the United States declares that "no state shall, without the consent of
congress, enter into agreement or compact with another state, or with a
foreign power." See 11 Pet: 1; 8 Wheat. 1 Bald. R. 60; 11 Pet. 185.