1. To defend against attack or criticism
2. To refuse to back down; remain solid under criticism or attack.
3. To resist or withstand wear, criticism, etc.; SYN. hold up.
4. When you stand up, you change from a sitting position to a standing position. Get up is similar to stand up.

1. Of a collar; standing up rather than folded down; SYN. stiff.
2. Requiring a standing position

1. Stand-up comedy; also; a performer of such comedy
2. A television broadcast in which the reporter or narrator faces the camera with the scene of the story in the background

When you stand people up, you do not arrive at their house as you have promised or at a social event or meeting where you are expected.