Meaning of “behind” - Learner’s Dictionary

behind

adverb us uk /bɪˈhaɪnd/
Extra Examples
Some runners are straggling a long way behind.She was striding down the street with her kids trotting behind.By this time she was a long way behind.The teacher asked him to stay behind after class.We were in a hurry and I think I must have left my keys behind.
BACK

A2 at or to the back of someone or something:

Somebody grabbed me from behind.
SLOWER

slower or later than someone else, or than you should be:

She's behind with the rent (= is late to pay it).
PLACE

A2 in the place where someone or something was before:

You go on ahead. I'll stay behind and tidy up.
When we got to the restaurant, I realized that I had left my purse behind.

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