| ̷ ̷ ̷ ̷| ̷ ̷ adjective
: occurring either completely or not at all : marked either by entire, complete, inclusive, or unqualified operation or effect or by none at all
in unequal degrees, rather than in all-or-none fashion — Walter Firey
an all-or-none reaction
a nerve cell has … an all-or-none response, like the trigger of a gun — E.C.Berkeley