Expound comes from Middle English expounden, from Old French espondre, from Latin exponere ('to set forth, explain'), from ex- ('out') + ponere ('to put, place'). Morphologically, the form is compositional: ex- marks part of the visible structure, while the remaining element supplies the lexical base. In present use, it is used as a verb meaning "to explain or present something in detail", so the historical material remains connected with the current sense rather than standing as bare ancestry. The wider English family includes derivatives such as expounder and related forms such as exposition, expositor, expository, and exponent, showing how the same historical material continues to organize neighboring vocabulary. The named historical forms include Old French espondre, Latin exponere, and Latin ponere, keeping the history tied to concrete forms rather than a loose resemblance.