/ ˈetɪmɒn; NAmE -mɑːn/ noun
( pl. ety·mons or ety·ma / -mə; NAmE /) ( linguistics ) a word or part of a word from which another word comes
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WORD ORIGIN
late 16th cent. (denoting the original form of a word): via Latin from Greek etumon true thing, neuter singular of etumos true.