Definition from Wiktionary, the free dictionary
Euphemistic and abbreviated form of pissed off.
- (idiomatic, colloquial, euphemistic) Annoyed, irritated, angry; depressed, fed up.
1972, Patrick M. McGrady, The love doctors, page 356:
- Wilbur was PO'd, of course. Didn't speak to her for six hours ...
2008, William Frank Buckley, The Reagan I Knew, page 198:
- ... told Nancy he was PO'd up to his keister with--pause! ...