hold someone up—
1. support a person physically; hold smb. upright:
- It took both of us to hold up the old man.
2. rob smb. using violence or threats:
- In Japan you won’t need to worry too much about being held up in the street and being robbed of your passport.
3. (hyperbolic) overcharge a person:
- I don’t eat at that restaurant anymore. They really held me up the last time I ate there.
4. detain a person; make smb. late:
- The traffic on the expressway held me up yesterday.
keep someone up—
1. = hold someone up 1:
- I could barely stand up myself, but I managed to keep up Ann until we got out of the smoke-filled room.
2. prevent smb. from going to bed; keep a person awake:
- “I hope I’m not keeping you up.” “No, we often keep up late.”
See also: keep someone down / keep someone under.