Tremor, n.
Etymology: [L., from tremere to tremble. See Tremble, v.]
A trembling; a shivering or shaking; a quivering or vibratory motion; as, the tremor of a person who is weak, infirm, or old. He fell into an universal tremor of all his joints. Harvey.
Shades of meaning
Fernald has no entry of its own for tremor; he lists it under fear.
He lists it without comment; the entries above explain its neighbors.