Meaning of “stumble” - Learner’s Dictionary

stumble

verb [ I ] uk us /ˈstʌmbl/
FALL

to step badly and almost fall over:

Mary stumbled on the loose rocks.
PAUSE

to make a mistake, such as pausing or repeating a word, while speaking or performing:

He kept stumbling over the same word.

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