rational

UK: ˈræʃənəl | US: ˈræʃənəl

Definition
  1. adj. based on reason or logic

  2. adj. capable of thinking clearly

  3. n. (Mathematics) a number expressible as a ratio of integers

Structure
rat <reckon/calculate>ion <noun suffix>al <adjective suffix>
Etymology

Derived from Latin rationalis ("of reason"), from ratio ("reckoning, calculation, reason"). The root rat- (from ratus, past participle of reri "to reckon") reflects the idea of logical judgment. The suffix -ion nominalizes the concept, while -al adapts it into an adjective. Over time, "rational" evolved from mathematical precision to broader logical reasoning.

Examples
  1. She made a rational decision after analyzing the data.

  2. Humans are considered rational beings.

  3. The debate required rational arguments, not emotional appeals.

  4. √2 is not a rational number.

  5. His rational approach solved the complex problem efficiently.