casual
casualness
infrequent
frequent
unfrequent
occasional
rarely
episodic
uncommonly
adventitiously
episodicity
incident
accidental
eternally
now and then
once in a while
at times
unoccasional
from time to time
occasionally
on occasion
now and again
unregular
sometimes
stated
unsuddenly
nongradual
heterochronic
unanticipatedly
seldom
precipitating
just like that
due course
periodically
uncertain
roughly
sporadically
recurrence
unusual
recurringly
nonsporadic
unrecurrent
nonrecurrent
unexpectable
semiregular
nonfrequent
I can't remember the last time
infrequently
oft
on-again, off-again
patchy
spasmodic
intermissive
off-time
expontaneous
common
inevitable
unexpectingly
unprecedential
nonprecedential
nonrecurring
unthoughted
incoincident
nonrandom
punctual
return
acute
inadvertent
periodic
surreption
habitually
non sequitur
here and there
every so often
inconstant
unpredicable
nonrecurrence
uncommonable
lippening
quasiperiodic
heteroclite
unhabitual
on a regular basis
opportunity seldom knocks twice
leading
noncommonable
semiperiodic
impreventable
ever
atypical