on top of

on top of

1. Atop
2. Very close to, in any orientation or in time.

   Living on top of one another in a refugee camp is stressful.

   At peak times, a telephone operator must handle a number of calls, one on top of the next.

3. (idiomatic) In addition to something else.

   . . . and on top of all that, I got a puncture!

4. (idiomatic) Fully informed about, and in control of, something; up to speed with.

   I have sorted out the problems and am now on top of the situation.

• on top
• top it all off