1. Adjective.  Optimal; being the best possibility.
  2. Adjective.  Perfect, flawless, having no defects.
  3. Adjective.  Existing only in the mind; conceptual, imaginary.
  4. Adjective.  (mathematics) Not actually present, but considered as present when limits at infinity are included.
  5. Noun.  A perfect standard of beauty, intellect etc., or a standard of excellence to aim at.
  6. Noun.  (mathematics, order theory) A non-empty lower set (of a partially ordered set) which is closed under binary suprema (a.k.a. joins).[].
  7. Noun.  (context, for example) A subring closed under multiplication by its containing ring.

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This entry was last updated on RefTopia from its source on 3/20/2012.