"necktie tied in the form of a bow or a knot with two loops," by 1887, from bow (n.) in the sense "ribbon or other fabric tied in a bow-knot" (by 1874) + tie (n.).
Entries linking to bow tie
bow v.1
[bend the body] Middle English bouen, from Old English bugan "to bend, become bent, have or assume a curved direction; to bow down, bend the body in condescension or reverence, to submit," also "to turn back" (class II strong verb; past tense beag, past participle bogen), from Proto-Germanic *bugon (source also of Dutch buigen, Middle Low German bugen, Old High German biogan, German biegen, Gothic biugan "to bend," Old Norse boginn "bent"), from *beugen, from PIE root *bheug- "to bend." Related: Bowed; bowing. To bow out "withdraw" is from 1942, from the notion of "exit with a bow or bows."
tie n.
Old English teag, "cord, band, thong, fetter," literally "that with which anything is tied," from Proto-Germanic *taugo (source also of Old Norse taug "tie," tygill "string"), from PIE root *deuk- "to lead" (source also of Old English teon "to draw, pull, drag").
Figurative sense is recorded from 1550s. Sense of "cravat, necktie" (usually a simple one knotted in front) first recorded 1761. The railway sense of "cross-beam between and beneath rails to keep them in place" is from 1857, American English. Meaning "equality between competitors" is first found 1670s, from notion of a connecting link. Tie-breaker is recorded from 1938. The figurative old school tie (1938) in its literal sense was a necktie of a characteristic pattern worn by former students of a particular English school.