v.1. To form a line: The students lined up at the front of the classroom. People are lining up to get tickets to the game.
2. To arrange some people or things in a line: The police lined the suspects up against the wall. We lined up some chairs in front of the stage. Customers were lined up waiting for the stores to open.
3. To organize something or someone for an event or activity; schedule something or someone: I've lined two interviews up for next week. The organizers lined up some great speakers for the rally. The senator is lining up support for the bill.
4. To straighten something, or put it in the correct position in relation to some other thing: I lined the text up with the edge of the page. The sniper lined up the rifle and fired two shots at the middle of the target. We lined up the holes and put the bolt through.
5. To be straight or in the correct position in relation to some other thing: The holes don't line up—I can't get the bolt in. Does this painting line up with the ceiling?
6. In American football, to take one's position in a formation before a snap or kickoff: The players lined up at the scrimmage line.