etymon

[ et-uh-mon ]
/ ˈɛt əˌmɒn /

noun, plural et·y·mons, et·y·ma [et-uh-muh] /ˈɛt ə mə/.

the linguistic form from which another form is historically derived, as the Latin cor “heart,” which is the etymon of English cordial, or the Indo-European *ḱ(e)rd-, which is the etymon of Latin cor, Greek kardía, Russian serdtse, and English heart.

Origin of etymon

1560–70; < Latin: the origin of a word < Greek étymon the essential meaning of a word seen in its origin or traced to its grammatical parts (neuter of étymos true, actual, real)
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British Dictionary definitions for etyma

etymon

/ (ˈɛtɪˌmɒn) /

noun plural -mons or -ma (-mə)

a form of a word or morpheme, usually the earliest recorded form or a reconstructed form, from which another word or morpheme is derived: the etymon of English "ewe" is Indo-European " * owi"

Word Origin for etymon

C16: via Latin, from Greek etumon basic meaning, from etumos true, actual
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012