Green’s Dictionary of Slang

Jock adj.

[Jock n. (2)]

Scottish.

[UK]T. Paulin ‘Desertmartin’ in Liberty Tree 16: A Jock squaddy glances down the street.
[UK](con. 1980s) I. Welsh Skagboys 13: You farking MI5 or what, you farking Jock cunt?!