1815, from Latin trigeminus "born in threes," as a noun, "triplets;" from tri- (see tri-) + geminus "born at the same birth" (see geminate (adj.)).
Entries linking to trigeminal
tri-
word-forming element meaning "three, having three, once every three," from Latin tres (neuter tria) or Greek treis, trias "three" (see three).
geminate adj.
"duplicated, found in pairs," early 15c., from Latin geminatus "twinned, equal," past participle of geminare "to double, repeat," related to geminus "twin, born together; paired, double," perhaps from PIE *yem- "to pair." As a verb, from 1630s. Related: Geminated; geminating; geminative.