Synonyms for Reason:

n.

common sense, acumen, vision, intuition, sanity, clarity, brilliance, wisdom, judgment. pragmatic, speculation, argumentation, sensible, ratiocination, balanced, mature, Clear-headed, Grounded, practical, rationalism, rational, logical, realistic. think over, assess, take a long hard look at someone/something, Because, by way of, think out, plan, take something into consideration, on account of. perish the thought, start, don't remind me, don't ask, it's a long story, keep it simple, skip it. warrant, true, foundation. account, rationalization, explain, explanation. why, proof, argument. necessity, call. sense. soundness, lucidity, Lucidness, marble, sane, saneness, wit. account (noun)
rationalization.
explanation for an action (noun)
account, justification, excuse, ground.
intellect (noun)
comprehension, cerebration, brain-power, brain, mentality, reasoning, mind, rationality, understanding, intellect, capacity, intelligence.
intelligence (noun)
mind.
mental analysis (noun)
lucidity, wisdom, acumen, understanding, rationalism, ratiocination, sanity, induction, logic, mentality, deduction, inference, reasonableness, speculation, argumentation, soundness, reasoning, rationalization, sense, brain, comprehension, rationality, saneness, judgment, wit, intellect, mind.
motive (noun)
ground.
pretext (noun)
plea, stratagem, affirmation, smoke screen, pretense, alibi, excuse, white lie, loop-hole, justification, rationale, pretext, claim, red herring.
reason (noun)
ground, brain work, cogitation, intellect, analysis, induction, rationality, logic, reason out, conceptualization, argue, grounds, cause, inference, reasonableness, thought, deduction, thinking, understanding, conclude, synthesis.
sanity (noun)
saneness.
sense (noun)
sense.
sound judgment (noun)
common sense.
thought (noun)
thinking.

v.

argue, persuade (verb)
debate.
mentally analyze (verb)
conclude, contemplate, deduce, study, speculate, deliberate, infer, cogitate, cerebrate, think, reflect.
reason (verb)
conceptualize, cogitate, synthesize, deduce, infer, induct, analyze, think.
think (verb)
debate, appraise, imagine, contemplate, speculate, deliberate, reflect, cerebrate, envision, meditate, muse, brood, concentrate, evaluate, weigh, consider, ponder, calculate, study.

Other synonyms:

rationalization, acumen, intuition, why, common sense, brilliance, saneness, foundation, judgment, ratiocination. rational, logical, wherefore, root, warrant, vision, explanation, Lucidness. balanced, marble, sane, soundness, explain, lucidity. necessity, motivation, account. proof. wit, sensible. point. force
impetus.
good sense
wisdom, sanity.
humanism
rationalism.
spur
incentive.
think
thought, cerebrate.

Usage examples for reason

  1. But that is not all the reason – Together by Robert Herrick (1868-1938)
  2. " Yes, I suppose that is the reason – A Daughter of the Vine by Gertrude Franklin Horn Atherton
  3. Did she have any reason – The Disturbing Charm by Berta Ruck