on top of

on top of  {prep.}

1. On the top of; standing or lying on; on.

When the player on the other team dropped the ball, Bill fell on top of it.

That high hill has a tower on top of it.

2.  {informal}

Very close to.

The elevator was so crowded that everybody was on top of each other.

I couldn't find my umbrella and then I realized I was almost on top of it.

3.  {informal}

In addition to; along with.

Mrs. Lane had many expenses and on top of everything else, her baby became ill.

Mary worked at the store all day and on top of that she had to baby-sit with her brother.

4.  {informal}

Managing very well; in control of.

Although his new job was very complicated, John was on top of it within a few weeks.

No matter what goes wrong, Mary always stays on top of it.

5. Knowing all about; not falling behind in information about; up-to-date on.

Mary stays on top of the news by reading newspapers and magazines.