etymon

UK: /ˈɛtɪˌmɒn/ US: (et′ə mon′)

WordReference Random House Unabridged Dictionary of American English © 2025

et•y•mon  (et′ə mon′), n., pl. -mons, -ma 

(-mə). 
1. 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.

• Greek étymon the essential meaning of a word seen in its origin or traced to its grammatical parts (neuter of étymos true, actual, real)
• Latin: the origin of a word
• 1560–70

Collins Concise English Dictionary © HarperCollins Publishers::

etymon / ˈɛtɪˌmɒn/ noun ( -mons, -ma / -mə/)

1. 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"

Etymology: 16th Century: via Latin, from Greek etumon basic meaning, from etumos true, actual