We found one dictionary that defines the word be on top of:

Phrases: be on top of things, to be on top of something, on be positioned on top of, to be on top of it, more... ▸ Words similar to be on top of ▸ Usage examples for be on top of ▸ Idioms related to be on top of ▸ Wikipedia articles (New!) ▸ Words that often appear near be on top of ▸ Rhymes of be on top of ▸ Invented words related to be on top of