Pronunciation: (rash'u-nl, rash'nl), [key]
1. agreeable to reason; reasonable; sensible: a rational plan for economic development.
2. having or exercising reason, sound judgment, or good sense: a calm and rational negotiator.
3. being in or characterized by full possession of one's reason; sane; lucid: The patient appeared perfectly rational.
4. endowed with the faculty of reason: rational beings.
5. of, pertaining to, or constituting reasoning powers: the rational faculty.
6. proceeding or derived from reason or based on reasoning: a rational explanation.
a. capable of being expressed exactly by a ratio of two integers.
b. (of a function) capable of being expressed exactly by a ratio of two polynomials.
8. Class. Pros.capable of measurement in terms of the metrical unit or mora.
Math.See rational number.
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.