■ adjective
1》 most suitable; perfect.
2》 desirable or perfect but existing only in the imagination: in an ~ world.
↘representing an abstract or hypothetical optimum.
■ noun a person or thing regarded as perfect.
↘a standard or principle to be aimed at.
Derivatives
~ly adverb
Origin
ME (as a term in Platonic philosophy, in the sense 'existing as an archetype'): from late L. ~is , from L. idea (see idea ).