Green’s Dictionary of Slang

deadbeat n.

[backform. f. deadbeat adj.]

1. [early 19C] a state of exhaustion.

2. [mid-19C] of things, a failure, a deception.

3. [mid-19C+] of people, a failure, a down-and-out.

4. in attrib. use of sense 3.

5. [mid-19C+] a malingerer, an idler, a wastrel.

6. [mid-19C+] a cadger, a sponge.

7. [late 19C] (US) a form of alcohol.

8. [late 19C+] one who reneges on their debts.