early 15c., "faithfulness, devotion," from Old French fidélité (15c.), from Latin fidelitatem (nominative fidelitas) "faithfulness, adherence, trustiness," from fidelis "faithful, true, trusty, sincere," from fides "faith" (from PIE root *bheidh- "to trust, confide, persuade"). From 1530s as "faithful adherence to truth or reality;" specifically of sound reproduction from 1878.
mid-15c., "to place trust or have faith," from Latin confidere "to trust in, rely firmly upon, believe," from assimilated form of com, here perhaps an intensive prefix (see com-), + fidere "to trust" (from PIE root *bheidh- "to trust, confide, persuade"). Meaning "to share a secret with, take into one's confidence" is from 1735; phrase confide in (someone) is from 1888. Related: Confided; confiding.
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 Original sense is obsolete; modern sense of "distrustful of oneself, not confident" is by 1713.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.
1610s, confident, "(male) person trusted with private affairs," from French confident (16c.), from Italian confidente "a trusty friend," literally "confident, trusty," from Latin confidentem (nominative confidens), present participle of confidere "to trust, confide," from assimilated form of com, here perhaps an intensive prefix (see com-), + fidere "to trust" (from PIE root *bheidh- "to trust, confide, persuade"). The spelling with -a- and the pronunciation with the stress on the last syllable came to predominate 18c. and might reflect the French pronunciation.
1530s, "to unite in a league or alliance," from Late Latin confoederatus, past participle of confoederare "to unite by a league," from assimilated form of com "with, together" (see con-) + foederare, from foedus (genitive foederis) "a league," from suffixed form of PIE root *bheidh- "to trust, confide, persuade."
The older verb was confeder (late 14c.), from Old French confederer, Medieval Latin confederare. Related: Confederated; confederating.
early 15c., dissuasioun, "advice or exhortation in opposition to something," from Old French dissuasion (14c.) and directly from Latin dissuasionem (nominative dissuasio) "an advice to the contrary," noun of action from past-participle stem of dissuadere "to advise against, oppose by argument," from dis- "off, against" (see dis-) + suadere "to urge, incite, promote, advise, persuade," literally "recommend as good" (related to suavis "sweet"), from PIE root *swād- "sweet, pleasant" (see sweet (adj.)).
From mid-16c. especially "to promise in marriage." The earlier form of the word was affy (Middle English affien "to trust, have faith; have faith in" c. 1300), from Old French afier. Related: Affianced; affiancing.