Definition of "heartbeat"

heartbeat

/ˈhɑːtˌbiːt/

noun
plural heartbeats
1. One pulsation of the heart; especially an irregular one, hence the emotion which causes it.
2. The rhythm at which a heart pulsates, a cardiac indicator.
3. A driving impulse or vital force; the vital center of something.
  Quotations
  Dream Body Recovery is just one of countless recovery houses that have cropped up in Miami, which has become the heartbeat of the B.B.L. boom in the United States. The average price of a B.B.L. nationwide is around $5,000, according to the American Society of Plastic Surgeons.
  2022 May 11, Sandra E. Garcia, “Butt Lifts Are Booming. Healing Is No Joke.”, in The New York Times Magazine‎
4. A very short space of time; an instant.
  Quotations
  Cause I love you more than life Take a bullet for you I swear, I swear In a heartbeat
  2014, “Bullet”, Robbie Williams et al. (lyrics)
5. (computing) A periodic signal generated by hardware or software to indicate normal operation or to synchronize other parts of a system.