1. [n]  the idea of something that is perfect; something that one hopes to attain
2. [n]  model of excellence or perfection of a kind; one having no equal
3. [adj]  constituting or existing only in the form of an idea or mental image or conception; "a poem or essay may be typical of its period in idea or ideal content"
4. [adj]  conforming to an ultimate standard of perfection or excellence; embodying an ideal
5. [adj]  represented in the abstract rather than as they really are
6. [adj]  of or relating to the philosophical doctrine of the reality of ideas

Ideal
Ideal

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1. \I*de"al\, a. [L. idealis: cf. F. id['e]al.]
   1. Existing in idea or thought; conceptional; intellectual;
      mental; as, ideal knowledge.
   2. Reaching an imaginary standard of excellence; fit for a
      model; faultless; as, ideal beauty. --Byron.
            There will always be a wide interval between
            practical and ideal excellence.       --Rambler.
   3. Existing in fancy or imagination only; visionary; unreal.
      ``Planning ideal common wealth.'' --Southey.
   4. Teaching the doctrine of idealism; as, the ideal theory or
      philosophy.
   5. (Math.) Imaginary.
   Syn: Intellectual; mental; visionary; fanciful; imaginary;
        unreal; impracticable; utopian.
   

2. \I*de"al\, n.
   A mental conception regarded as a standard of perfection; a
   model of excellence, beauty, etc.
         The ideal is to be attained by selecting and assembling
         in one whole the beauties and perfections which are
         usually seen in different individuals, excluding
         everything defective or unseemly, so as to form a type
         or model of the species. Thus, the Apollo Belvedere is
         the ideal of the beauty and proportion of the human
         frame.                                   --Fleming.
   {Beau ideal}. See {Beau ideal}.
   

1. 1. Ideal DEductive Applicative Language. A language by Pier Bosco and Elio Giovannetti combining Miranda and Prolog. Function definitions can have a guard condition (introduced by ":-") which is a conjunction of equalities between arbitrary terms, including functions. These guards are solved by normal Prolog resolution and unification. It was originally compiled into C-Prolog but was eventually to be compiled to K-leaf.

   2. A numerical constraint language written by Van Wyk of Stanford in 1980 for typesetting graphics in documents. It was inspired partly by Metafont and is distributed as part of Troff.

   ["A High-Level Language for Specifying Pictures", C.J. Van Wyk, ACM Trans Graphics 1(2):163-182 (Apr 1982)].

2. In domain theory, a non-empty, downward closed subset which is also closed under binary least upper bounds. I.e. anything less than an element is also an element and the least upper bound of any two elements is also an element.