- (subordinating) except under the circumstances that; except on the condition that: they'll sell it unless he hears otherwise
WordReference Random House Learner's Dictionary of American English © 2026
un•less /ʌnˈlɛs/USA pronunciation
conj.
WordReference Random House Unabridged Dictionary of American English © 2026- except under the circumstances that:We'll be there at nine, unless the train is late.
un•less
(un les′, ən-),USA pronunciation conj.
prep.
- except under the circumstances that:I'll be there at nine, unless the train is late.
prep.
- except;
but;
save:Nothing will come of it, unless disaster.
- 1400–50; late Middle English prepositional phrase on less (also o less(e), earlier upon less) on a lesser footing or condition (than); first used as a preposition and conj. in the early 16th century; see on, less
Collins Concise English Dictionary © HarperCollins Publishers::
unless /ʌnˈlɛs/ conj
'unless' also found in these entries (note: many are not synonyms or translations):
barring
- borne
- but
- caveat emptor
- decree nisi
- except
- excepting
- inertia
- interlock
- law of supply and demand
- Newton's laws of motion
- nisi
- nude
- prima-facie evidence
- Shields
- squire
- sunset clause
- suspended sentence
- tonnage
- year
- aa
- abet
- alone
- and
- approval
- barrelhead
- bear
- body
- borrow
- bring
- cock-and-bull story
- cream
- crescent
- damp
- deploy
- ers
- frozen
- great-circle sailing
- greed
- hapten
- inertial system
- jeer
- keep
- law of motion
- lemures
- Malthusian
- mamma
- mullet
- murdrum
- name