Merriam-Webster Collegiate Dictionary - ideal

 I. adjective  Etymology: Middle English ydeall, from Late Latin ~is, from Latin idea  Date: 15th century  1. existing as an archetypal idea  2.  a. existing as a mental image or in fancy or imagination only; broadly lacking practicality  b. relating to or constituting mental images, ideas, or conceptions  3.  a. of, relating to, or embodying an ~ ~ beauty  b. conforming exactly to an ~, law, or standard ; perfect an ~ gas — compare real 2b(3)  4. of or relating to philosophical ~ism  II. noun  Date: 15th century  1. a standard of perfection, beauty, or excellence  2. one regarded as exemplifying an ~ and often taken as a model for imitation  3. an ultimate object or aim of endeavor ; goal  4. a subset of a mathematical ring that is closed under addition and subtraction and contains the products of any given element of the subset with each element of the ring  Synonyms: see model  • ~less adjective