Of something abstract: in accordance with reason; not irrational, absurd, or ridiculous; just, legitimate; due, fitting.

Originally Scottish. Of a thing: in accordance with or conformable to reason; reasonable, just, fair.

Of a statement, idea, judgement, etc.: in accordance with reason, truth, or reality; right; true; factually correct. Often with connotations of…

Based on or derived from reason or reasoning, esp. as opposed to emotion, intuition, instinct, etc.

In accordance with fact, truth, or reason; free from error; exact, true, accurate; right. Said also of persons, in reference to their statements…