Well over a thousand years ago, the word accent was used in the Old English language as a synonym of "mark" or "sign". Then it died out and nobody used it until the late 1300s, when they borrowed it again from Old French acent. By the sixteenth century, the word had also branched out in definition to relate to emphases, language pronunciations, tones, and more. Acent and the original accent were both borrowed from Latin accentus, which meant "song added to speech" (reflecting the current "intonation" meaning) and was composed of the prefix ad-, or "to" (from a very similar Proto-Indo-European reconstruction), and the root canere, meaning "to sing" (that's also thought to be PIE, from kan, with the same definition). Usage of the word accent peaked in the 1780s but has been on the rise recently.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.