Oxford Advanced American Dictionary

Definition of or conjunction from the Oxford Advanced Learner's Dictionary

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or

conjunction
or pronunciation English ɔː(r) or pronunciation American ɔːr
 
1 used to introduce another possibilityIs your sister older or younger than you?Are you coming or not?Is it a boy or a girl?It can be black, white or grey. compare either… or…2 used in negative sentences when mentioning two or more thingsHe can't read or write.There are people without homes, jobs or family. compare neither… nor…3 (also or else) used to warn or advise somebody that something bad could happen; otherwiseTurn the heat down or it'll burn.4 used between two numbers to show approximately how manyThere were six or seven of us there.5 used to introduce a word or phrase that explains or means the same as anothergeology, or the science of the earth's crustIt weighs a kilo, or just over two pounds.6 used to say why something must be trueHe must like her, or he wouldn't keep calling her.7 used to introduce a contrasting ideaHe was lying—or was he?
Idioms

or so

about
It'll cost €100 or so.

or somebody/something/somewhere

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somebody/something/somewhere or other

(informal) used when you are not exactly sure about a person, thing or placeHe's a factory supervisor or something.‘Who said so?’ ‘Oh, somebody or other. I can't remember who it was.’