rational

(noun): A rational number: a number that can be expressed as the quotient of two integers.
(adjective): Capable of reasoning.
(adjective): Logically sound; not contradictory or otherwise absurd.
(adjective): (of a person or personal characteristics) Healthy or balanced intellectually; exhibiting reasonableness.
(adjective): Of a number, capable of being expressed as the ratio of two integers.
(adjective): Of an algebraic expression, capable of being expressed as the ratio of two polynomials.
(adjective): Expressing the type, structure, relations, and reactions of a compound; graphic; said of formulae.
(adjective): Expressing a physical object.