only
only if
only when
under no circumstances
in no way
not while pussy's a cat
when two Sundays meet
when two Sundays come together
never ever
nevah
never've
uneverted
nooit
unreminded
nary
nonrecurring
unpreceded
nonexistent
unoccasioned
isolated
Neveruary
when Hell freezes over
omniabsent
at the earliest
nondermal
unprecedented
in a pig's eye
uneven
never
ne'er
unpredicated
at the latest
nonexcepted
nonrepeated
unoften
infrequently
nondegreased
unsurmised
unpredisposed
noninterim
ungathered
at no time
if pigs had wings
when pigs fly
unchanced
incoincident
at latter Lammas
unwaited
seldomly
nonrepeat