Green’s Dictionary of Slang

1. the penis.

1540

D. Lyndsay Satyre of Thrie Estaits V ii: Methink my pillock will nocht ly doun. Hold doun your heid, ye ladroune loun!

2. a general term of abuse.

1958		C. Lee diary 20 Feb. in Eight Bells & Top Masts (2001) 61: Didn’t I know there had been a war? [...] He called me a pillock.
1967		J. Burke Till Death Us Do Part 166: We haven’t got a phone, you silly great pilloch [sic].
1983		(con. 1950s) D. Nobbs Second From Last in the Sack Race 265: There’s no cause to call him a pillock.
1996		K. Lette Mad Cows 19: If he’s such a pillock [...] then why’d ya shag him?
2006		D. Mitchell Black Swan Green 125: Mrs Thatcher fixed her stained-glass blue eyes on that pillock.

3. a fool, a simpleton.

1970		Galton & Simpson ‘Cuckoo in the Nest’ Steptoe and Son [TV script] You daft pillock!
1982		P. Theroux London Embassy 151: Course he works here, you pillock!
1990		Gaiman & Pratchett Good Omens 195: ‘1666?’ ‘No, you great pillock! That was the fire! The Plague was 1665!’.
2000		Guardian 20 Jan. 22: That would show what a stupid pillock I was.

4. see pillicock n.