reason

n. & v.
—n.
1 a motive, cause, or justification (has good reasons for doing this; there is no reason to be angry).
2 a fact adduced or serving as this (I can give you my reasons).
3 the intellectual faculty by which conclusions are drawn from premisses.
4 sanity (has lost his reason).
5 Logic a premiss of a syllogism, esp. a minor premiss when given after the conclusion.
6 a faculty transcending the understanding and providing a priori principles; intuition.
7 sense; sensible conduct; what is right or practical or practicable; moderation.
—v.
1 intr. form or try to reach conclusions by connected thought.
2 intr. (foll. by with) use an argument (with a person) by way of persuasion.
3 tr. (foll. by that + clause) conclude or assert in argument.
4 tr. (foll. by why, whether, what + clause) discuss; ask oneself.
5 tr. (foll. by into, out of) persuade or move by argument (I reasoned them out of their fears).
6 tr. (foll. by out) think or work out (consequences etc.).
7 tr. (often as reasoned adj.) express in logical or argumentative form.
8 tr. embody reason in (an amendment etc.).
Phrases and idioms:
by reason of owing to. in (or within) reason within the bounds of sense or moderation. it stands to reason (often foll. by that + clause) it is evident or logical. listen to reason be persuaded to act sensibly. see reason acknowledge the force of an argument. with reason justifiably.
Derivatives:
reasoner n. reasoning n. reasonless adj.
Etymology: ME f. OF reisun, res(o)un, raisoner, ult. f. L ratio -onis f. reri rat- consider