Meaning of “overrun” - Learner’s Dictionary

overrun

verb uk us /ˌəʊvəˈrʌn/ (present participle overrunning, past tense overran, past participle overrun)
FILL [ T ]

If something unpleasant overruns a place, it fills it in large numbers:

[ often passive ] The house was overrun by rats.
Troops overran the city.
CONTINUE [ I ] UK

to continue for a longer time than planned:

Sorry I'm late, but the meeting overran by 20 minutes.

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