1545–55; < Latintrājectus (past participle of trāicere to cast, throw over or across), equivalent to trā- (variant of trāns-trans-) + -jec- (combining form of jacere to throw) + -tus past participle suffix
Related formstra·jec·tion, noun
the curve described by a projectile, rocket, or the like in its flight.
Geometry. a curve or surface that cuts all the curves or surfaces of a given system at a constant angle.
Origin of trajectory
1660–70; < New Latintrājectōria, noun use of feminine of Medieval Latintrājectōrius cast-ing over. See traject, -tory1
Related formstra·jec·tile[truh-jek-til, -tahyl]/trəˈdʒɛk tɪl, -taɪl/, adjectivetra·jec·tion[truh-jek-shuh n]/trəˈdʒɛk ʃən/, noun
1690s, from Modern Latin trajectoria, from fem. of trajectorius "of or pertaining to throwing across," from Latin traiectus "thrown over or across," past participle of traicere "throw across," from Latin trans- "across" (see trans-) + icere, combining form of iacere "to throw" (see jet (v.)). Used in Late Latin and Middle English to mean "a funnel."