Etymology
Advertisement
mistrust (n.)

"lack of confidence, suspicion," late 14c., from mis- (1) "bad, wrong" + trust (n.). Related: Mistrustful; mistrustfulness.

Related entries & more 
Advertisement
mistrust (v.)

"doubt, regard with jealousy or suspicion," late 14c., mistrusten, from mis- (1) "badly, wrongly" + trust (v.). Related: Mistrusted; mistrusting.

Related entries & more 
suspect (adj.)
early 14c., "suspected of wrongdoing, under suspicion;" mid-14c., "regarded with mistrust, liable to arouse suspicion," from Old French suspect (14c.), from Latin suspectus "suspected, regarded with suspicion or mistrust," past participle of suspicere "look up at, look upward," figuratively "look up to, admire, respect;" also "look at secretly, look askance at," hence, figuratively, "mistrust, regard with suspicion," from assimilated form of sub "up to" (see sub-) + specere "to look at" (from PIE root *spek- "to observe"). The notion behind the word is "look at secretly," hence, "look at distrustfully."
Related entries & more 
suspect (v.)

mid-15c. (implied in suspected), from suspect (adj.) and in part from French suspecter or directly from Latin suspectare "to mistrust," frequentative of suspicere. Related: Suspecting.

Related entries & more 
distrust (n.)

"absence of trust; doubt or suspicion," 1510s, from dis- + trust (n.). "The etymologically correct form is mistrust, in which both elements are Teutonic" [Klein].

Related entries & more 
Advertisement
suspect (n.)
"a suspected person," 1590s, from suspect (adj.). Earlier as a noun it meant "a suspicion, mistrust" (late 14c.).
Related entries & more 
distrust (v.)

early 15c., "have a doubt or dread of" (a sense now obsolete); 1540s, "withhold trust or confidence from; doubt or suspect," from dis- + trust (v.) . "The etymologically correct form is mistrust, in which both elements are Teutonic" [Klein]. Related: Distrusted; distrusting.

Related entries & more 
suspicion (n.)
c. 1300, "act of suspecting; unverified conjecture of wrongdoing; mistrust, distrust," from Anglo-French suspecioun, corresponding to Old French suspicion, sospeçon "mistrust, suspicion" (Modern French soupçon), from Late Latin suspectionem (nominative suspectio) "mistrust, suspicion, fear, awe," noun of state from past participle stem of Latin suspicere "look up at" (see suspect (adj.)). Spelling in English influenced 14c. by learned Old French forms closer to Latin suspicionem. Used as a verb meaning "to suspect," it figures in literary representations of U.S. Western (Kentucky) slang from 1830s.

"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").
Related entries & more 
diffidence (n.)
Origin and meaning of diffidence

c. 1400, "distrust, want of confidence, doubt of the ability or disposition of others," from Latin diffidentia "mistrust, distrust, want of confidence," from diffidere "to mistrust, lack confidence," from dis- "away" (see dis-) + fidere "to trust" (from PIE root *bheidh- "to trust, confide, persuade"). The opposite of confidence. Original sense (distrust of others) is obsolete; the modern sense is of "distrust of oneself, want of confidence in one's ability, worth, or fitness" (1650s), hence "retiring disposition, modest reserve."  

Diffidence is a defect: it is an undue distrust of self, with fear of being censured for failure, tending to unfit one for duty. [Century Dictionary]
Related entries & more 
diffident (adj.)
Origin and meaning of diffident

mid-15c., "distrustful, wanting confidence in another's power," from Latin diffidentem (nominative diffidens), present participle of diffidere "to mistrust, lack confidence," from dis- "away" (see dis-) + fidere "to trust" (from PIE root *bheidh- "to trust, confide, persuade"). Original sense is obsolete; modern sense of "distrustful of oneself, not confident" is by 1713. Compare diffidence. Related: Diffidently.

Related entries & more