[in.stan.ta.neous] adj [ML instantaneus, fr. instant-, instans, n.] (1651) 1: done, occurring, or acting without any perceptible duration of time "death was ~"
2: done without any delay being purposely introduced "took ~ action to correct the abuse"
3: occurring or present at a particular instant "~ velocity" -- in.stan.ta.ne.ity n -- in.stan.ta.neous.ly adv -- in.stan.ta.neous.ness n