Optimal; being the best possibility. / Perfect, flawless, having no defects. / Pertaining to ideas, or to a given idea. / Existing only in the mind; conceptual, imaginary.

A perfect standard of beauty, intellect etc., or a standard of excellence to aim at. / (algebra, ring theory) A subring closed under multiplication by its containing ring.

(philosophy) An abstract archetype of a given thing, compared to which real-life examples are seen as imperfect approximations; pure essence, as opposed to actual examples.

The worship of idols. / The excessive admiration of somebody or something.

(transitive) To establish the identity of someone or something. / (transitive) To disclose the identity of someone. / (transitive, biology) To establish the taxonomic classification of an organism.

(strictly) The act of identifying (i.e., which one, which thing).

(derogatory) A person of low general intelligence. / (derogatory) A person who makes stupid decisions; a fool.

(uncommon) idiotic, stupid

(algebra) An element of an algebraic structure, generally denoted 1, which is an identity for a multiplicative operation (generally denoted × or *, or by concatenation).

(algebra) An element of an algebraic structure, generally denoted 0, which is an identity for an additive operation (generally denoted +). That is, x + 0 = 0 + x = x for any x in the structure.