1881, from hyphen + -ate (2). The earlier verb was simply hyphen (1814). Related: Hyphenated; hyphenating. Hyphenated American "immigrant citizen perceived as having divided loyalties" is attested from 1889.
"short dash used to connect two words or separate one," 1620s, from Late Latin hyphen, from Greek hyphen "mark joining two syllables or words," probably indicating how they were to be said or sung. This was a noun use of an adverb meaning "together, in one," literally "under one," from hypo "under" (from PIE root *upo "under") + hen, neuter of heis "one," from PIE root *sem- (1) "one; as one, together with."
verbal suffix for Latin verbs in -are, identical with -ate (1). Old English commonly made verbs from adjectives by adding a verbal ending to the word (such as gnornian "be sad, mourn," gnorn "sad, depressed"), but as the inflections wore off English words in late Old and early Middle English, there came to be no difference between the adjective and the verb in dry, empty, warm, etc. Thus accustomed to the identity of adjectival and verbal forms of a word, the English, when they began to expand their Latin-based vocabulary after c. 1500, simply made verbs from Latin past-participial adjectives without changing their form (such as aggravate, substantiate) and it became the custom that Latin verbs were Englished from their past participle stems.
<a href="https://www.etymonline.com/word/hyphenate">Etymology of hyphenate by etymonline</a>
Harper, D. (n.d.). Etymology of hyphenate. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/hyphenate