faculty (n.)youdaoicibaDictYouDict
late 14c., "ability, opportunity, means, resources," from Old French faculte "skill, accomplishment, learning" (14c., Modern French faculté) and directly from Latin facultatem (nominative facultas) "power, ability, capability, opportunity; sufficient number, abundance, wealth," from *facli-tat-s, from facilis (see facile).

Academic sense "branch of knowledge" (late 14c.) was in Old French and probably was the earliest in English (it is attested in Anglo-Latin from late 12c.), on notion of "ability in knowledge" or "body of persons on whom are conferred specific professional powers." Originally each department was a faculty; the use in reference to the whole teaching staff of an entire college dates from 1767. Related: Facultative. The Latin words facultas and facilitas "were originally different forms of the same word; the latter, owing to its more obvious relationship to the adj., retained the primary sense of 'easiness', which the former had ceased to have before the classical period." [OED]
savoir-faire (n.)youdaoicibaDictYouDict
"instinctive knowledge of the right course of action in any circumstance," 1815, from French, literally "to know (how) to do," from savoir "to know" (from Latin sapere; see sapient) + faire (from Latin facere "to make, do;" see factitious). French also has savoir-vivre "ability in good society; knowledge of customs in the world."
voice (n.)youdaoicibaDictYouDict
late 13c., "sound made by the human mouth," from Old French voiz "voice, speech; word, saying, rumor, report" (Modern French voix), from Latin vocem (nominative vox) "voice, sound, utterance, cry, call, speech, sentence, language, word" (source also of Italian voce, Spanish voz), related to vocare "to call," from PIE root *wekw- "give vocal utterance, speak" (cognates: Sanskrit vakti "speaks, says," vacas- "word;" Avestan vac- "speak, say;" Greek eipon (aorist) "spoke, said," epos "word;" Old Prussian wackis "cry;" German er-wähnen "to mention").

Replaced Old English stefn. Meaning "ability in a singer" is first attested c. 1600. Meaning "expression of feeling, etc." (in reference to groups of people, etc., such as Voice of America) is recorded from late 14c. Meaning "invisible spirit or force that directs or suggests" (especially in the context of insanity, as in hear voices in (one's) head) is from 1911.