c. 1400, resounen, "to question (someone)," also "to challenge," from Old French resoner, raisoner "speak, discuss; argue; address; speak to," from Late Latin rationare "to discourse," from Latin ratio "reckoning, understanding, motive, cause," from ratus, past participle of reri "to reckon, think" (from PIE root *re- "to reason, count").
The intransitive sense of "to think in a logical manner, exercise the faculty of reason" is from 1590s; transitive sense of "employ reasoning (with someone)" is from 1680s. Related: Reasoned; reasoning.
"Suspicion" words in other Indo-European languages also tend to be words for "think" or "look" with prefixes meaning "under, behind;" such as Greek hypopsia (hypo "under," opsis "sight"), hyponoia (noein "to think"); Lettish aizduomas (aiz "behind," duomat "think"); Russian podozrenie (Slavic podu "under," Old Church Slavonic zireti "see, look"); Dutch achterdocht (achter "behind," denken "to think").
mid-15c., opinen, "express an opinion or opinions; to think, suppose," also transitive, "be of the opinion that," from Old French oppiner, opiner (15c.) and directly from Latin opinari "have an opinion, be of opinion, suppose, conjecture, think, judge," which is of unknown origin. It is traditionally considered to be related to optare "to desire, choose" (see option), but de Vaan's sources find the evidence of this weak. Related: Opined; opining.
c. 1300, deinen, "think worthy, think well of, regard as suited to one's dignity," from Old French deignier (Modern French daigner) and directly from Latin dignari "to deem worthy or fit" (source of Italian degnare, Spanish deñar), from dignus "worthy," from PIE root *dek- "to take, accept." Sense of "take or accept graciously" led to that of "condescend" (1580s), with an infinitive for an object. Related: Deigned; deigning.
"state of mind accompanying an act which condemns the perpetrator to criminal punishment," Latin, literally "guilty mind;" from mens "mind," from PIE root *men- (1) "to think."