n. 1 a very brief portion of time; an instant. 2 a short period of time (wait a moment) (see also MINUTE(1)). 3 an exact or particular point of time (at last the moment arrived; I came the moment you called). 4 importance (of no great moment). 5 Physics & Mech. etc. a the turning effect produced by a force acting at a distance on an object. b this effect expressed as the product of the force and the distance from its line of action to a point. at the moment at this time; now. in a moment 1 very soon. 2 instantly. man (or woman etc.) of the moment the one of importance at the time in question. moment of inertia Physics the quantity by which the angular acceleration of a body must be multiplied to give corresponding torque. moment of truth a time of crisis or test (orig. the final sword-thrust in a bullfight). not for a (or one) moment never; not at all. this moment immediately; at once (come here this moment).
[ ME f. OF f. L momentum: see MOMENTUM ]