Root word

• Earlier form of a word
• Original form of a word
• Original word form
• A word's original form
• Base word
• Older form of a word

The Collaborative International Dictionary Word definitions in The Collaborative International Dictionary
Etymon \Et"y*mon\, n.; pl. E. Etymons , Gr. Etyma . [L., fr. Gr. 'e`tymon the true literal sense of a word according to its derivation, an etymon, fr. ? true, real, prob, akin to Skr. sotya, E. sooth. See Sooth .] An original form; primitive word; ...

Wiktionary Word definitions in Wiktionary
n. A source word of a given word.

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
"primitive word," 1570s, from Greek etymon , neuter of etymos "true, real, actual" (see etymology ). Classical Greek used etymon as an adverb, "truly, really." Related: Etymic .