uncommonly
unoccasional
infrequent
unfrequent
rarely
occasional
infrequently
seldom
common as pig tracks
sometimes
once in a blue moon
semioccasionally
on occasion
semioccasional
sporadical
nonfrequent
occasionally
now and then
once in a while
from time to time
now and again
at times
as often as not
uncommon
accidental
episodic
I can't remember the last time
periodically
sporadically
seldom or ever
geason
nonrare
semiregular
nonprevalent
unprevalent
oft
frequent
seldomly
nonrecurring
casual
usually
stated
heterochronic
unregular
lippening
episodicity
nonsporadic
sporadic
by and large
unusual
adventitiously
seldomness
on and off
unexpectable
different
off and on
unwonted
rareish
unoften
semirare
most of the time
more often than not
atypical
uncommonable
noncommonable
on average
every so often
erratically
punctual
uncommonplace
unusualness
noncommon
semiperiodic
unique
opportunity seldom knocks twice
every now and then
now
sometime
once in a purple moon
remarkable
aleatorily
unprecedential
out of the way
nonprecedential
roughly