= instantaneous, adj.

Occupying less than a moment of time.

= instantaneous, adj.

Occurring or operating in an instant; done, completed, or reaching completion without any perceptible lapse of time.

Involving or characterized by rapidity of action or execution; swift; (sometimes) hasty, precipitate, impetuous, superficial.

Originally: †ready, at hand, immediate (obsolete). Now: of the nature of a magical transformation; rapid, quick, instantaneous.

Quick, sudden, instantaneous; jerky.

figurative. Sudden, instant; rapid.

Having no duration.

Occurring, executed in, or lasting a fraction of a second; timed or calculated to a fraction of a second; sudden, instantaneous.

Occurring, made, delivered, etc., without delay or change of place; immediate. Also (of a report or account): made by a person who was present at…