One who departs; a person who leaves or goes away from a place.
From depart (from Old French departir, from Latin dispartire meaning 'to divide' or 'to separate') + -er (agent suffix). An archaic or formal term for someone leaving.
Departer is a rare gem in English—it's grammatically perfect and logically obvious, yet we almost never use it, preferring 'someone who leaves' instead, which shows how English often rejects perfectly valid words for no reason.
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