Meaning of “top” - Learner’s Dictionary

top

adjective [ always before noun ] us uk /tɒp/
BEST

B1 the best, most important, or most successful:

He's one of the country's top athletes.

More examples

HIGHEST

B1 at the highest part of something:

I can't reach the top shelf.
I had to undo the top button of my jeans.

(Definition of “top adjective” from the Cambridge Learner’s Dictionary © Cambridge University Press)