1. To join someone or something in a line. I lined up with Tammy in the cafeteria. She heaved a sigh or resignation and lined up with all the other customers at the checkout.

2. To cause or direct someone or something to form or get into a line with other people or things. In this usage, a noun or pronoun can be used before or after "up." The police officer lined up the suspect with several other men to see if the witness picked him out. Line the book up with the other ones by the same author.

3. To form or get into a line in the same orientation as something else. In this usage, a noun or pronoun can be used before or after "up." Make sure each tile you lay lines up perfectly with the others—the homeowners aren't paying for crooked tiling. We want the north side of the football field to line up with the south side of the high school.

4. To be in agreement or accordance with something; to concur with or corroborate some piece of information. Her testimony lines up with the defendant's alibi. That's right, sir, Tom's estimates line up perfectly with my own calculations.

5. To organize or schedule a meeting or event with another person or a group of people. In this usage, a noun or pronoun can be used before or after "up." We need to line up a meeting with the CEOs of the two companies. We're trying to line up a silent auction to benefit victims of last month's hurricane.