spur of the moment (adjective) spur-of-the-moment: extemporaneous
Sinonime: ad hoc, ad-lib,
automatic, autoschediastic, by ear,
casual,
expedient, extemporary, extempore,
fake*,
free,
immediate,
impromptu, improv, improvisatory, improvised, improviso,
informal, jamming, made-up, makeshift, offhand, on impulse, on-the-spot,
snap,
spontaneous, toss off, toss out,
unplanned, unpremeditated, unprepared, unrehearsed, unstudied, winging it