on top—
1. resting on smth.:
- An imposing enamel teapot stands on top, quietly stewing.
2. in the lead; winning:
- The horse that everyone had expected would be on top actually came in third.
3. (also: at the top) in a position of power or authority:
- The men on top are always trampling down those who are trying to climb up.
up top—
1. = on top 3:
- If you need more proof that the men up top are ignoring our needs, the Government Accounting Office has just released a new study.
2. (Air Force) in the sky:
- You reveal your position to the aircraft up top and it is time to move fairly fast.
3. (sl.) in terms of mental capacity:
- Peg, you’ve got enough up top for both of us.