Trajectile, a word rarely used, refers to an object that is projected or thrown through the air. There are a few synonyms that can be used instead of trajectile like missile, projectile, dart, or bolt. Each of these synonyms can be used to describe an object that is launched or hurled with force. Other related words can also include things like bullet, round, or shell. When describing a moving object, words like flying, soaring, or hurtling could be useful. Overall, while trajectile is an infrequently used word, its synonyms can provide a more common frame of reference for describing the movement of projectiles.