tremor

nouns

an involuntary vibration (as if from illness or fear)
shudder, tremor
a small earthquake
earth tremor, microseism, tremor
shaking or trembling (usually resulting from weakness or stress or disease)
tremor
is a part of
a degenerative disorder of the central nervous system characterized by tremor and impaired muscular coordination
Parkinson's, Parkinson's disease, Parkinson's syndrome, Parkinsonism, paralysis agitans, shaking palsy
is a type of (narrower)
a shaky motion
"the shaking of his fingers as he lit his pipe"
palpitation, quiver, quivering, shakiness, shaking, trembling, vibration

verbs

shake with seismic vibrations
"The earth was quaking"
quake, tremor