Trajectory
late 17th century: from modern Latin trajectoria (feminine), from Latin traject- ‘thrown across’, from the verb traicere, from trans- ‘across’ + jacere ‘to throw’.
wiktionary
From New Latin trāiectōrium, from trāiectōrius(“of or pertaining to throwing across”), from Latin trāiectus(“thrown over or across”), past participle of trāiciō, from trans-(“across, beyond”) (see trans-) + iaciō(“to throw”) (from Proto-Indo-European *(H)yeh₁-(“to throw, impel”)). Middle French and Middle English had trajectorie (“end of a funnel”), from Latin trāiectōrium.
etymonline
trajectory (n.)
"path described by a body moving under the influence of given forces," 1690s, from Modern Latin trajectorium, from trajectorius "of or pertaining to throwing across," from Latin traiectus "thrown over or across," past participle of traicere "throw across, shoot across," from Latin trans "across, beyond" (see trans-) + icere, combining form of iacere "to throw" (from PIE root *ye- "to throw, impel"). Middle French and Middle English had trajectorie as "end of a funnel," from Latin traiectorium.
