piss (v.)

"to urinate, discharge the fluid secreted by the kidneys and stored in the urinary bladder," c. 1300, pissen, from Old French pissier "urinate" (12c.), from Vulgar Latin *pissiare, of imitative origin. To piss away (money, etc.) is from 1948. Related: Pissed; pissing. Pissing while (1550s) once meant "a short time."

He shall not piss my money against the wall; he shall not have my money to spend in liquor. [Grose, "Classical Dictionary of the Vulgar Tongue," 3rd edition, 1796]

To piss money on the walls "throw money around recklessly" is attested from 1540s.

He who once a good name gets,
May piss a bed, and say he sweats.
["Dictionary of Buckish Slang, University Wit and Pickpocket Eloquence," London, 1811] 

piss (n.)

"urine," late 14c., from piss (v.). As a pure intensifier (piss-poor, piss-ugly, etc.) it dates from 1940, popularized in World War II. Piss and vinegar "vim, energy" is attested from 1942. Piss-prophet "one who diagnoses diseases by inspection of urine" is attested from 1620s. Piss proud "erect upon awakening" is attested from 1796.

updated on July 27, 2022

Definitions of piss from WordNet
piss (n.)
liquid excretory product;
Synonyms: urine / pee / piddle / weewee / water
piss (n.)
informal terms for urination;
Synonyms: peeing / pee / pissing
piss (v.)
eliminate urine;
Synonyms: make / urinate / piddle / puddle / micturate / pee / pee-pee / make water / relieve oneself / take a leak / spend a penny / wee / wee-wee / pass water
From, not affiliated with etymonline.