weḱ-
“to speak, to voice”speak, voice, word
Root for speaking, yielding Latin vox (voice), Greek epos (word), English voice.
Discussion
The PIE root *weḱ- (to speak, to voice, to utter) produced the Indo-European vocabulary of vocal expression — a family of words that connects the physical act of making sound with the social acts of advocating, invoking, and provoking.
Latin vōx (voice — genitive vōcis) continues the root directly and is the source of the central English vocabulary: voice (via Old French), vocal (pertaining to the voice), vocabulary (the words one voices), vocation (a calling — vocātiō, the act of being called/voiced to a purpose), advocate (ad-vocāre, to call toward oneself, to speak on behalf of), provoke (prō-vocāre, to call forth — to stimulate a response by voicing a challenge), invoke (in-vocāre, to call upon — especially a deity), revoke (re-vocāre, to call back — to withdraw what was voiced), convoke (to call together), and evoke (to call out of — to summon from memory or feeling).
The sheer number of English words built on the Latin prefixed forms of vocāre makes *weḱ- one of the most institutionally productive PIE roots: the legal system uses advocate and revoke, the religious tradition uses invoke and vocation, the political sphere uses provoke and convoke, and everyday English uses voice and vocabulary.
Greek épos (ἔπος, "word, speech, epic poetry") preserves the root with the expected Greek treatment. The derivative epikós gave English epic — the long narrative poem that preserves the spoken word of heroic tradition. The word is literally "that which is voiced."
Sanskrit vákti ("he speaks") and the related vā́c- (voice, speech — cognate with Latin vōx) confirm the Indo-Iranian reflex. The Vedic Vāc (Speech) was deified as a goddess, reflecting the sacred status of vocal utterance in Vedic ritual.
The English word voice, borrowed from Old French voiz (from Latin vōcem), displaced the native Germanic word for voice — a characteristic pattern where a French-Latin borrowing replaced the inherited term after the Norman Conquest.
Notes
Pokorny 1135-1136. English voice, vocal, vowel, invoke, evoke.