TRANSIENT a. 4 definitions
it were, moving over or across a space or scene viewed, and then disappearing; hence, of short duration; not permanent; not lasting or durable; not stationary; passing; fleeting; brief; transitory; as, transient pleasure. "Measured this transient world." Milton.
TRANSITORY a.
Continuing only for a short time; not enduring; fleeting; evanescent. Comfort and succor all those who, in this transitory life, are in trouble. Bk. of Com. Prayer. It was not the transitory light of a comet, which shines and glows for a wile, and then . . . vanishes into nothing. South. Transitory action (Law), an act…
TREBUCHET; TREBUCKET n. 3 definitions
Middle Ages for throwing stones, etc. It acted by means of a great weight fastened to the short arm of a lever, which, being let fall, raised the end of the long arm with great velocity, hurling stones with much force.