Origin of deadbeat
- a person who makes a habit of avoiding or evading his or her responsibilities or debts
- (as modifier)a deadbeat dad
- (of a system) returning to an equilibrium position with little or no oscillation
- (of an instrument or indicator) indicating a true reading without oscillation
"worthless sponging idler," 1863, American English slang, perhaps originally Civil War slang, from dead (adj.) + beat. Earlier used colloquially as an adjectival expression to mean "completely beaten" (1821), and perhaps the base notion is of "worn out, good for nothing." It is noted in a British source from 1861 as a term for "a pensioner."
In England "dead beat" means worn out, used up. ... But here, "dead beat" is used, as a substantive, to mean a scoundrel, a shiftless, swindling vagabond. We hear it said that such a man is a beat or a dead beat. The phrase thus used is not even good slang. It is neither humorous nor descriptive. There is not in it even a perversion of the sense of the words of which it is composed. Its origin is quite beyond conjecture. ["Americanisms," in "The Galaxy," January 1878]
It also was used of a kind of regulating mechanism in pendulum clocks.
Defeated; also exhausted. For example, That horse was dead beat before the race even began, or, as Charles Dickens put it in Martin Chuzzlewit (1843): “Pull off my boots for me ... I am quite knocked up. Dead beat.” [Slang; first half of 1800s]
Also, deadbeat. A lazy person or loafer; also, one who does not pay debts. For example, Her housemate knew she was a deadbeat, shirking her share of the chores, or He's a deadbeat; don't count on getting that money back. [Slang; second half of 1800s]