Longman Dictionary of Contemporary English
speech impediment
noun
EXAMPLES FROM CORPUS
▪ A speech impediment did nothing to stop him from preaching.
▪ He also had a speech impediment.
▪ He had a nervous twitch and a speech impediment.
▪ I kept silent, thinking that he might have an embarrassing speech impediment.
Wiktionary
speech impediment
n. any speech disorder