or

An appositional word or phrase introduced by or is set off by commas:

            He brandished his khanjar, or dagger, as he spoke.

When or introduces the final member of a series of three or more, it is preceded by a comma:

            coffee, tea, or milk

After a compound subject or a series connected with or, the verb agrees with the final member:

            wine or cocktails are served

            soft drinks, cocktails, or wine is served