beat vs heartbeat

beat and heartbeat both are nouns.

Word	Noun	Adjective	Verb	Adverb
beat	Yes	Yes	Yes	No
heartbeat	Yes	No	No	No

As nouns, beat and heartbeat are synonyms defined as:

beat and heartbeat: the rhythmic contraction and expansion of the arteries with each beat of the heart

Other synonyms of beat include pulsation, pulse.

beat (noun)	heartbeat (noun)
the act of beating to windward; sailing as close as possible to the direction from which the wind is blowing	an animating or vital unifying force
a stroke or blow	the rhythmic contraction and expansion of the arteries with each beat of the heart
a regular rate of repetition	a very short time (as the time it takes the eye to blink or the heart to beat)
the basic rhythmic unit in a piece of music
(prosody) the accent in a metrical foot of verse
the rhythmic contraction and expansion of the arteries with each beat of the heart
the sound of stroke or blow
a regular route for a sentry or policeman
a member of the beat generation; a nonconformist in dress and behavior
a single pulsation of an oscillation produced by adding two waves of different frequencies; has a frequency equal to the difference between the two oscillations

beat (adjective)	heartbeat (adjective)
very tired

beat (verb)	heartbeat (verb)
wear out completely
be a mystery or bewildering to
come out better in a competition, race, or conflict
beat through cleverness and wit
hit repeatedly
give a beating to; subject to a beating, either as a punishment or as an act of aggression
stir vigorously
strike (a part of one's own body) repeatedly, as in great emotion or in accompaniment to music
strike (water or bushes) repeatedly to rouse animals for hunting
shape by beating
make by pounding or trampling
produce a rhythm by striking repeatedly
move rhythmically
sail with much tacking or with difficulty
move with a flapping motion
indicate by beating, as with the fingers or drumsticks
move with a thrashing motion
move with or as if with a regular alternating motion
make a rhythmic sound
make a sound like a clock or a timer
glare or strike with great intensity
avoid paying
be superior