v.1. To fall out of something: My card must have dropped out of the bag at some point.
2. To make or let something or someone fall out of something: I dropped the stones out of the window.
3. To withdraw from participation in something, as a game, club, or school: The committee is trying to determine why so many students were dropping out. I dropped out of algebra because it was too hard. I dropped history out of my schedule this term.
4. To withdraw from established society, especially due to disillusionment with conventional values: My cousin dropped out and moved to the tropics.
5. To omit something: This computer drops out the semicolons. The old stereo drops the bass out.
6. To be omitted: When words are contracted, some sounds or letters drop out.