Longman Dictionary of Contemporary English - or

~ conjunction 1 used between two things or before the last in a list of possibilities, things that people can choose from etc  (Do you want to leave now or would you rather set off later? | Was it London, Paris or Rome where you first met Maxim? | or anything/something spoken (=or something of the same kind))  (Would you like a coffee or something? | I wasn't trying to push in or anything. | either... or...)  (If either Lennie or Miranda calls, I'm not at home.)  (- compare either3) 2 used after a negative v when you mean not one thing and also not another thing  (He doesn't have a television or a video. | Sonia never cleans or even offers to wash the dishes.) 3 used to warn or advise someone that if they do not do something, something they do not want will happen  (Wear your coat or you'll catch cold. | or else)  (You have to roll the clothes very tightly or else they won't all fit in the rucksack. | You'd better be there, or else. (=used to threaten someone)) 4 used to correct something that you have said or to give more specific information  (It's going to snow tomorrow, or that's what the forecast says. | She was born in Saigon, or Ho Chi Minh City as it is now called. | or rather)  (The computer software is old, or rather very out of date.) 5 used to explain why something happens or to show that something must be true  (He must be very drunk or he wouldn't keep falling down. | or else)  (It's either a coincidence they're so alike, or else they are related in some way.) 6 a minute/a mile/twenty etc or so a particular amount or a little more  (They had to wait an hour or so for the police to arrive.) 7 a minute/a dollar etc or two a small amount or number of something  (I saw Nigel leaving a second or two ago.)