Origins
The Latin word 'vōx' — meaning 'voice, sound, speech, word' — is the source of one of the most cohesive word families in English. Through the noun vōx and the derived verb vocāre ('to call'), Latin gave English everything from 'voice' and 'vocal' to 'vocation' and 'provoke,' all united by the fundamental human act of using the voice.
Vōx traces to the Proto-Indo-European root *wekʷ-, meaning 'to speak' or 'to say.' This root has cognates across the family. Greek ἔπος (épos) meant 'word' and, in the plural, 'epic poetry' — Homer's Iliad and Odyssey were ἔπη (épē), spoken words, reflecting the oral tradition in which they were composed. Sanskrit वाच् (vāc) meant 'voice, speech' and was personified as the goddess Vāc in the Rigveda — the divine voice that brought the world into being through utterance. Avestan had vāxš ('voice'). The Germanic branch largely lost this root, replacing it with other words for speech and voice.
In Latin, the initial PIE *w was preserved as v (Latin v was pronounced /w/ in Classical Latin, later becoming /v/). Vōx was a third-declension feminine noun with the oblique stem vōc-. It covered voice as a physical instrument (the sound produced by the vocal cords), a particular sound or tone, a word or expression, speech or language in general, and — by extension — a vote or expression of will.
Proto-Indo-European Roots
The most basic English descendant is 'voice' itself, which arrived through Old French voiz (from Vulgar Latin *vōce) around 1290. 'Vocal' (from Latin vocālis, 'of the voice') followed. 'Vowel' comes from Old French vouel, from Latin vocālis (littera), 'a voiced letter' — the sounds of speech that are produced with open vocal resonance, without obstruction.
The Latin verb vocāre ('to call') — a denominative verb derived from vōx ('voice') — generated the largest branch of the family. 'Vocation' (from Latin vocātiō, 'a calling') entered English around 1420, originally in the religious sense of a divine calling. 'Avocation' (from ab- + vocāre, 'to call away from') originally meant a distraction from one's vocation, then came to mean a hobby or secondary pursuit. 'Vocabulary' (from Medieval Latin vocābulārium, from vocābulum, 'a name, a designation,' from vocāre) means literally 'a collection of names' — the words by which we call things.
The compound verbs of vocāre form a particularly coherent group. 'Invoke' (from in- + vocāre, 'to call upon') means to summon or appeal to. 'Evoke' (from ē- + vocāre, 'to call out') means to summon forth, to call up a memory or response. 'Provoke' (from prō- + vocāre, 'to call forth') originally meant to challenge or summon to action; the hostile sense ('to anger') is an extension. 'Revoke' (from re- + vocāre, 'to call back') means to withdraw or cancel. 'Convoke' (from con- + vocāre, 'to call together') means to summon an assembly. Each preserves the core meaning of vocāre — calling — with a different directional prefix.
Later History
'Advocate' (from ad- + vocāre, 'to call to') was originally a legal term: an advocātus was someone 'called to' assist in a legal case, a supporter or defender. The word's evolution from legal defender to general supporter or champion mirrors the broadening of many legal terms in English. 'Advocacy' preserves the active sense of speaking on someone's behalf — using one's voice for another.
'Equivocal' (from aequus, 'equal' + vōx, 'voice') means 'of equal voices' — having two equally valid interpretations, ambiguous. To 'equivocate' is to speak with two voices, to be deliberately ambiguous. 'Univocal' (from ūnus, 'one' + vōx) means 'having one voice' — clear and unambiguous.
The phrase 'vox populi' ('the voice of the people') has been used in English since the seventeenth century, often in the extended form 'vox populi, vox Dei' ('the voice of the people is the voice of God'). This ancient maxim — sometimes endorsed, sometimes cited skeptically — reflects the political power of the concept embedded in vōx: that voice and political agency are inseparable, that to have a voice is to have power.
Latin Roots
The modern media brand 'Vox' and the term 'vox pop' (a broadcast journalism technique of interviewing ordinary people) both draw directly on the Latin word. In music, 'vox humana' ('the human voice') is a pipe organ stop designed to imitate singing. In anatomy, the 'vocal cords' preserve the Latin root. The ubiquity of vōx and its descendants in English reflects a culture that has always placed the voice — speaking, calling, naming, voting — at the center of public life.