/ ɔː(r); NAmE / conjunction
1.
used to introduce another possibility :
Is 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 things :
He 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 sb that sth bad could happen; otherwise :
Turn the heat down or it'll burn.
4.
used between two numbers to show approximately how many :
There were six or seven of us there.
5.
used to introduce a word or phrase that explains or means the same as another :
geology, or the science of the earth's crust
It weighs a kilo, or just over two pounds.
6.
used to say why sth must be true :
He must like her, or he wouldn't keep calling her.
7.
used to introduce a contrasting idea :
He was lying—or was he?
•
IDIOMS
- or so
- or somebody / something / somewhere | somebody / something / somewhere or other
••
WORD ORIGIN
Middle English : a reduced form of the obsolete conjunction other (which superseded Old English oththe or ), of uncertain ultimate origin.