Instantaneous

прилагательное мгновенный; немедленный, незамедлительный Например: instantaneous effect — мгновенный результат Синоним(ы): momentary, immediate

Большой англо-русский словарь

Instantaneous

adjective Etymology: Medieval Latin instantaneus, from instant-, instans, noun 1. done, occurring, or acting without any perceptible duration of time Example: death was instantaneous 2. done without any delay being purposely introduced Example: took instantaneous action to correct the abuse 3. occurring or present at a particular instant Example: instantaneous velocityinstantaneity nouninstantaneously adverbinstantaneousness noun

Merriam-Webster's Collegiate Dictionary