instant

English instant comes through Old French instant from Latin īnstāns, the present participle of īnstō, 'to stand upon, be nearby, press urgently' — itself built from in- ('on, upon') plus stō ('to stand').

In Middle English, instant meant 'an infinitely short period of time,' inherited from the Old French adjective sense of 'assiduous, at hand' — a shift from something pressing and near at hand to something over in a flash.

It shares its root stō ('to stand') with English state, both tracing back to the same Latin verb for standing.