Meaning of “trail” - Learner’s Dictionary

trail

verb uk us /treɪl/
FOLLOW [ T ]

to follow someone, especially without them knowing, in order to watch or catch them:

He suspected he was being trailed by undercover police.
HANG DOWN [ I, T ] UK

to hang down and touch the ground, or to make something do this:

Your coat's trailing in the mud.
LOWER SCORE [ I, T ]

to have a lower score than someone else, especially in a sporting event:

City were trailing United 2-1 at half time.

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