instantaneity Definition

instantaneous
adj

1. Done, happening or occurring at once, very quickly or in an instant; immediate.

Example: The poison has an instantaneous effect
Thesaurus: immediate, instant, rapid, prompt, unhesitating, on-the-spot; Antonym: delayed, gradual.

Derivative: instantaneously
adverb

In an instant
Thesaurus: immediately, instantly, rapidly, at once, on the spot, straight away, there and then, unhesitatingly, promptly.

Derivative: instantaneousness
noun

Etymology: 17c: from Latin instantaneus, from instare to be present.