stuttering

To speak with a spasmodic repetition of vocal sounds.

“He stuttered a few words of thanks.”

To exhaust a gas with difficulty

“The engine of the old car stuttered going up the slope. I was stuttering after the marathon.”

A speech disorder in which the flow of speech is disrupted by involuntary repetitions and prolongations of sounds, syllables, words or phrases, and by involuntary silent pauses or blocks in which the stutterer is unable to produce sounds.

An instance of stuttering.

That stutters.

Hesitant.