Origins
The verb 'provoke' entered English in the late fourteenth century from Old French 'provoquer,' itself from Latin 'prōvocāre.' The Latin word is transparently composed of two elements: the prefix 'prō-' (forth, forward) and the verb 'vocāre' (to call), making its literal meaning 'to call forth.' The underlying PIE root is *wekʷ-, meaning 'to speak' or 'to voice,' which produced one of the most prolific word families in the Latin-derived vocabulary of English.
In classical Latin, 'prōvocāre' had a concrete military and legal meaning before it acquired its more general sense. On the battlefield, to provoke the enemy was to call them forward, to challenge them to advance and engage. In Roman law, 'prōvocātiō' was the right of a Roman citizen to appeal a magistrate's capital sentence to the popular assembly — literally to 'call forth' the judgment of the people. This legal right, 'prōvocātiō ad populum,' was considered one of the fundamental guarantees of Roman republican liberty, enshrined in the Lex Valeria of 509 BCE, traditionally one of the first laws of the Roman Republic.
The semantic shift from 'to call forth' to 'to anger, to incite' occurred gradually through the metaphorical extension that was already present in Latin. If you call someone out to fight, you are challenging them, stirring them up, goading them — the emotional dimension was implicit in the physical act. By the time 'provoquer' entered Old French, the word carried both the concrete sense of challenging and the abstract sense of inciting emotion.
Middle English
English adopted the word with both senses intact. Chaucer and his contemporaries used 'provoke' to mean both 'to challenge' and 'to stir up.' Over the following centuries, the challenge-to-combat sense faded while the emotional sense strengthened, and by the seventeenth century, 'provoke' primarily meant to anger or irritate someone. The legal sense survived in specialized usage — 'provocation' remains a term of art in criminal law, where it can serve as a partial defense to a charge of murder.
The Latin verb 'vocāre' generated a remarkable family of English words, all built by attaching different prefixes to the same root. 'Evoke' (ē- + vocāre) means to call out or summon forth. 'Revoke' (re- + vocāre) means to call back, to cancel. 'Invoke' (in- + vocāre) means to call upon, to appeal to. 'Convoke' (con- + vocāre) means to call together. 'Advocate' (ad- + vocāre) is literally one who is called to your side. 'Equivocate' uses 'aequi-' (equal) + 'vocāre' to describe speaking with equal voice on both sides — deliberately ambiguous speech.
Beyond the '-voke' and '-vocate' compounds, 'vocāre' produced 'vocal,' 'voice' (through Old French 'voiz' from Latin 'vōx'), 'vocation' (a calling), 'vocabulary' (words for calling things), and 'vowel' (from Latin 'vōcālis littera,' literally 'vocal letter'). All of these descend from the same PIE root *wekʷ-, which also produced Sanskrit 'vák' (speech, voice) and Greek 'épos' (word, song — the source of 'epic').
Word Formation
The word 'provocative' appeared in English in the mid-fifteenth century and originally meant 'tending to call forth or stimulate,' often in a medical context — a provocative remedy was one that stimulated an organ or bodily function. The modern sexual connotation of 'provocative' developed in the eighteenth century, extending the idea of 'calling forth' to the arousal of desire. The noun 'provocateur,' borrowed directly from French, is most familiar in the compound 'agent provocateur' — someone who provokes others into committing illegal acts, a concept that dates to eighteenth-century French police practices.