the world > time > duration > shortness or brevity in time > [adjective] > of infinitesimal or imperceptible division of time (3)
imperceived1624
Not perceived or discerned; unnoticed, undetected.
momentaneous1706
Mathematics. Designating the increment in the value of a time-varying quantity that occurs in an infinitesimal period of time. Cf. moment, n. 3b, mome…