ideal

/aɪˈdiː.əl/

#2,953 of the most-used English words

noun

1. A perfect standard of beauty, intellect etc., or a standard of excellence to aim at.
2. A subring closed under multiplication by its containing ring.
3. (lattice theory) A non-empty lower set (of a partially ordered set) which is closed under binary suprema (a.k.a. joins).
4. A collection of sets, considered small or negligible, such that every subset of each member and the union of any two members are also members of the collection.

Similar: Lie ideal

adjective

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