abnormally
at infrequent intervals
barely
few
hardly
hardly ever
incredibly
infrequent
infrequently
irregularly
little
not often
occasional
occasionally
rare
rarely
scarce
scarcely
scarcely ever
seldom if ever
sparsely
sporadic
sporadically
uncommon
uncommonly
uncustomarily
unexpectedly
unfrequent
unfrequently
unnaturally
unoften
unordinarily
unusually
very seldom
frequently
often