(1):

(v. i.) To quaver or shake, as sound; to be tremulous; as the voice trembles.

(2):

(n.) An involuntary shaking or quivering.

(3):

(v. i.) To shake involuntarily, as with fear, cold, or weakness; to quake; to quiver; to shiver; to shudder; - said of a person or an animal.

(4):

(v. i.) To totter; to shake; - said of a thing.