the.com/spontaneousness
The unrehearsed yes, doing the heavy lifting that spontaneity already does better with fewer syllables.
means The quality of acting on impulse, without planning or external prompting — the same thing as spontaneity, just heavier.
from From Latin spontaneus, of one's own accord, plus a teetering pile of English suffixes (-ous, -ness) that doubled down where one would do.
Redundant twinSpontaneity says the same with less effort.
Root meaningLatin sponte means of one's free will.
Suffix stackingTwo endings glued onto one tired adjective.