or

Từ điển Oxford Advanced Learner 8th

or BrE [ɔː(r)] NAmE [ɔːr] 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 ▪ ↑somebody or other
See also: ↑or else

Word Origin:
[or] Middle English: a reduced form of the obsolete conjunction other (which superseded Old English oththe ‘or’), of uncertain ultimate origin.

• Từ đồng nghĩa / Synonyms:
  operating room, OR, operating theater, operating theatre, surgery, Oregon, Beaver State