tremble

Totremble is to shake involuntarily, often out of fear or because you are cold. (verb)

When you feel great fear about something, this is an example of a situation where you tremble with fear.
When you are freezing cold and start shaking, this is an example of a situation where you tremble.
When your voice quivers, this is an example of a situation where your voice trembles.

Tremble is a quiver or shake, often that occurs because of fear or cold. (noun)

When your voice is quivering, this is an example of a situation where there is a tremble in your voice.

See tremble in Webster's New World College Dictionary