tremble >> ˈtrɛmb(ə)l
Definition: [verb] (of a person, a part of the body, or the voice) shake involuntarily, typically as a result of anxiety, excitement, or frailty.
Example: Isobel was trembling with excitement
Definition: [noun] a trembling feeling, movement, or sound.
Example: there was a slight tremble in his voice
Definition: [noun] a physical or emotional condition marked by trembling.