The Collaborative International Dictionary of English v.0.48:

Abstract \Ab"stract`\ (#; 277), a. [L. abstractus, p. p. of
   abstrahere to draw from, separate; ab, abs + trahere to draw.
   See Trace.]
   1. Withdraw; separate. [Obs.]
      [1913 Webster]

            The more abstract . . . we are from the body.
                                                  --Norris.
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   2. Considered apart from any application to a particular
      object; separated from matter; existing in the mind only;
      as, abstract truth, abstract numbers. Hence: ideal;
      abstruse; difficult.
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   3. (Logic)
      (a) Expressing a particular property of an object viewed
          apart from the other properties which constitute it;
          -- opposed to concrete; as, honesty is an abstract
          word. --J. S. Mill.
      (b) Resulting from the mental faculty of abstraction;
          general as opposed to particular; as, "reptile" is an
          abstract or general name. --Locke.
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                A concrete name is a name which stands for a
                thing; an abstract name which stands for an
                attribute of a thing. A practice has grown up in
                more modern times, which, if not introduced by
                Locke, has gained currency from his example, of
                applying the expression "abstract name" to all
                names which are the result of abstraction and
                generalization, and consequently to all general
                names, instead of confining it to the names of
                attributes.                       --J. S. Mill.
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   4. Abstracted; absent in mind. "Abstract, as in a trance."
      --Milton.
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   An abstract idea (Metaph.), an idea separated from a
      complex object, or from other ideas which naturally
      accompany it; as the solidity of marble when contemplated
      apart from its color or figure.

   Abstract terms, those which express abstract ideas, as
      beauty, whiteness, roundness, without regarding any object
      in which they exist; or abstract terms are the names of
      orders, genera or species of things, in which there is a
      combination of similar qualities.

   Abstract numbers (Math.), numbers used without application
      to things, as 6, 8, 10; but when applied to any thing, as
      6 feet, 10 men, they become concrete.

   Abstract mathematics or Pure mathematics. See
      Mathematics.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Abstract \Ab*stract"\, v. t.
   To perform the process of abstraction. [R.]
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         I own myself able to abstract in one sense. --Berkeley.
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The Collaborative International Dictionary of English v.0.48:

Abstract \Ab*stract"\, v. t. [imp. & p. p. Abstracted; p. pr.
   & vb. n. Abstracting.] [See Abstract, a.]
   [1913 Webster]
   1. To withdraw; to separate; to take away.
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            He was incapable of forming any opinion or
            resolution abstracted from his own prejudices. --Sir
                                                  W. Scott.
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   2. To draw off in respect to interest or attention; as, his
      was wholly abstracted by other objects.
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            The young stranger had been abstracted and silent.
                                                  --Blackw. Mag.
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   3. To separate, as ideas, by the operation of the mind; to
      consider by itself; to contemplate separately, as a
      quality or attribute. --Whately.
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   4. To epitomize; to abridge. --Franklin.
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   5. To take secretly or dishonestly; to purloin; as, to
      abstract goods from a parcel, or money from a till.
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            Von Rosen had quietly abstracted the bearing-reins
            from the harness.                     --W. Black.
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   6. (Chem.) To separate, as the more volatile or soluble parts
      of a substance, by distillation or other chemical
      processes. In this sense extract is now more generally
      used.
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The Collaborative International Dictionary of English v.0.48:

Abstract \Ab"stract`\, n. [See Abstract, a.]
   1. That which comprises or concentrates in itself the
      essential qualities of a larger thing or of several
      things. Specifically: A summary or an epitome, as of a
      treatise or book, or of a statement; a brief.
      [1913 Webster]

            An abstract of every treatise he had read. --Watts.
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            Man, the abstract
            Of all perfection, which the workmanship
            Of Heaven hath modeled.               --Ford.
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   2. A state of separation from other things; as, to consider a
      subject in the abstract, or apart from other associated
      things.
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   3. An abstract term.
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            The concretes "father" and "son" have, or might
            have, the abstracts "paternity" and "filiety." --J.
                                                  S. Mill.
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   4. (Med.) A powdered solid extract of a vegetable substance
      mixed with lactose in such proportion that one part of the
      abstract represents two parts of the original substance.
      [1913 Webster + AS]

   Abstract of title (Law), a document which provides a
      summary of the history of ownership of a parcel of real
      estate, including the conveyances and mortgages; also
      called brief of title.
      [1913 Webster + PJC]

   Syn: Abridgment; compendium; epitome; synopsis. See
        Abridgment.
        [1913 Webster]

WordNet (r) 3.0 (2006):

abstract
    adj 1: existing only in the mind; separated from embodiment;
           "abstract words like `truth' and `justice'" [ant:
           concrete]
    2: not representing or imitating external reality or the objects
       of nature; "a large abstract painting" [syn: abstract,
       abstractionist, nonfigurative, nonobjective]
    3: dealing with a subject in the abstract without practical
       purpose or intention; "abstract reasoning"; "abstract
       science"
    n 1: a concept or idea not associated with any specific
         instance; "he loved her only in the abstract--not in
         person" [syn: abstraction, abstract]
    2: a sketchy summary of the main points of an argument or theory
       [syn: outline, synopsis, abstract, precis]
    v 1: consider a concept without thinking of a specific example;
         consider abstractly or theoretically
    2: make off with belongings of others [syn: pilfer, cabbage,
       purloin, pinch, abstract, snarf, swipe, hook,
       sneak, filch, nobble, lift]
    3: consider apart from a particular case or instance; "Let's
       abstract away from this particular example"
    4: give an abstract (of)

Moby Thesaurus II by Grady Ward, 1.0:

279 Moby Thesaurus words for "abstract":
   abate, abbreviate, abbreviation, abbreviature, abrade, abrege,
   abridge, abridgment, abstract idea, abstraction, abstruse,
   academic, altarpiece, and, annex, apocope, appropriate, arcane,
   armchair, bag, bate, bland, block print, bob, boil down, boost,
   borrow, breviary, brief, broad, capsule, capsulize, cast off,
   cast out, chuck, clear, clear away, clear out, clear the decks,
   clip, collage, collective, color print, colorless, compend,
   compress, compression, conceptual, condensation, condense,
   condensed version, conjectural, conspectus, contract, cop, copy,
   crib, crop, curtail, curtailment, cut, cut back, cut down,
   cut off short, cut out, cut short, cyclorama, daub, decrease,
   deduct, deep, defraud, deport, depreciate, derogate, detached,
   detract, digest, diminish, diptych, disconnect, disengage,
   disinterested, disparage, dispassionate, dispose of, dissociate,
   divide, dock, draft, drain, eat away, eject, elide, eliminate,
   elision, ellipsis, embezzle, engraving, epitome, epitomize,
   eradicate, erode, esoteric, essence, exile, expatriate, expel,
   extort, extract, featureless, filch, file away, foreshorten,
   foreshortening, fresco, general, generalized, generic, get quit of,
   get rid of, get shut of, head, hidden, hook, hypothetic,
   hypothetical, icon, ideal, ideational, illumination, illustration,
   image, impair, impersonal, impractical, indefinite, indeterminate,
   intellectual, leach, lessen, lift, likeness, liquidate,
   make off with, metaphysical, miniature, montage, moot, mosaic, mow,
   mural, nebulous, neutral, nip, nonspecific, notional, occult,
   outlaw, outline, overview, palm, pandect, panorama, part,
   photograph, pick out, picture, pilfer, pinch, poach, poker-faced,
   poll, pollard, postulatory, precis, print, profound, prune, purge,
   purify, purloin, reap, recap, recapitulate, recapitulation,
   recondite, reduce, reduction, refine, remove, representation,
   reproduction, resume, retrench, retrenchment, review, root out,
   root up, rub away, rubric, run away with, rustle, scrounge, secret,
   separate, shave, shear, shoplift, shorten, shortened version,
   shortening, skeleton, sketch, snare, snatch, snitch, snub,
   speculative, stained glass window, steal, stencil, still life,
   strike off, strike out, stunt, subduct, subtract, sum up,
   summarize, summary, summation, survey, swindle, swipe, syllabus,
   symbolic, syncope, synopsis, synopsize, tableau, take, take away,
   take from, take in, tapestry, telescope, telescoping, theoretical,
   thieve, thin, thin out, throw over, throw overboard,
   thumbnail sketch, topical outline, transcendent, transcendental,
   trim, triptych, truncate, truncation, unapplied, uncharacterized,
   uncouple, undemonstrable, undifferentiated, unpractical,
   unspecified, utopian, vague, visionary, walk off with,
   wall painting, wear away, weed, weed out, wide, withdraw



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

abstract

    A description of a concept that leaves out some
   information or details in order to simplify it in some useful
   way.

   Abstraction is a powerful technique that is applied in many
   areas of computing and elsewhere.  For example: abstract
   class, data abstraction, abstract interpretation,
   abstract syntax, Hardware Abstraction Layer.

   (2009-12-09)