Or

1. To suggest that only one possibility can be realized, excluding one or the other: "You can study hard for this exam or you can fail."
2. To suggest the inclusive combination of alternatives: "We can broil chicken on the grill tonight, or we can just eat leftovers.
3. To suggest a refinement of the first clause: "Smith College is the premier all-women's college in the country, or so it seems to most Smith College alumnae."
4. To suggest a restatement or "correction" of the first part of the sentence: "There are no rattlesnakes in this canyon, or so our guide tells us."
5. To suggest a negative condition: "The New Hampshire state motto is the rather grim "Live free or die."
6. To suggest a negative alternative without the use of an imperative (see use of and above): "They must approve his political style or they wouldn't keep electing him mayor."