- introducing the second of two possibilities: beer or wine
- introducing any of the possibilities in a series, but usually used only before the last: apples or pears or plums; apples, pears, or plums
- introducing a synonymous word or phrase: botany, or the science of plants
- introducing the second of two possibilities when the first is introduced by either or whether: either go or stay; decide whether to go or stay
- Old Poet. substituted for either or whether as the first correlative: “or in the heart or in the head”
Origin of or
ME, in form a contr. of other, auther, either, but actually from Old English oththe (in ?ther ... oththe, either ... or)