rational

Meanings

1. 1
   adj

   Based on clear, sensible thinking rather than emotion.

   We need a calm, rational discussion about the problem.

2. 2
   adj

   Able to think clearly and reason.

   Humans are rational creatures.

3. 3
   adj

   (mathematics) Able to be written as a fraction of two whole numbers.

   One half is a rational number, but the square root of two is not.

From Old French rational, from Medieval Latin rationale (“a pontifical stole, a pallium, an ornament worn over the chasuble”), neuter of Latin rationalis (“rational”), for which see the first etymology. Translation of λογεῖον (logeîon) or perhaps λόγιον (lógion, “oracle”) in the Septuagint version of Exodus 28.

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