To Falter

1. To waver or be unsteady; to weaken or trail off.
2. (transitive, intransitive) To stammer; to utter with hesitation, or in a weak and trembling manner.
3. To fail in distinctness or regularity of exercise; said of the mind or of thought.
4. To stumble.
5. (figuratively) To lose faith or vigor; to doubt or abandon (a cause).
6. To hesitate in purpose or action.
7. To cleanse or sift, as barley.