Executioner comes from execution + -er, from Latin executio, from exsequi ('to follow out, carry out, punish'), from ex- ('out') + sequi ('to follow'). Morphologically, the account is both compositional and suffixal: ex- and -er marks the visible structure by which the older base becomes the modern form. In present use, it is used as a noun meaning "a person who carries out a sentence of death", so the historical material remains connected with the current sense rather than standing as bare ancestry. The wider English family includes related forms such as execute, execution, and executor, showing how the same historical material continues to organize neighboring vocabulary. The named historical forms include Latin exsequi and Latin sequi, keeping the history tied to concrete forms rather than a loose resemblance. Its semantic neighborhood includes hangman, headsman, slayer, and killer, locating the modern specialization without adding a new origin story.