unprepared
ad lib
ad libitum
ad-lib
ad-libbing
arrangement
at short notice
at sight
by ear
cadenza
caught napping
caught off balance
caught short
extemporaneous
extemporaneously
extemporaneousness
extemporarily
extemporariness
extemporary
extempore
extemporization
extemporized
flourish
haphazard
hasty
hot lick
improvisation
improvisatorial
improvise
improvised
improvision
improviso
interpolation
jury-rig
jury-rigged
lick
makeshift
measure
off the cuff
off the hip
off-the-cuff
offhand
on sight
out of hand
playing by ear
precipitate
pro tempore
quick
address
musical passage
passage
speech
annual
elaborate
farewell
festive
grand
inaugural
informal
interminable
lengthy
memorable
nightly
occasional
outdoor
upcoming