tremor vs foreshock

tremor and foreshock both are nouns.

Word	Noun	Adjective	Verb	Adverb
tremor	Yes	No	Yes	No
foreshock	Yes	No	No	No

As nouns, foreshock is a hyponym of tremor; that is, foreshock is a word with a more specific, narrower meaning than tremor:

Other hyponyms of tremor include aftershock.

tremor (noun)	foreshock (noun)
an involuntary vibration (as if from illness or fear)	a tremor preceding an earthquake
a small earthquake
shaking or trembling (usually resulting from weakness or stress or disease)

tremor (verb)	foreshock (verb)
shake with seismic vibrations