Green’s Dictionary of Slang

Irish (moss), the n.

[rhy. sl.]

(Aus.) King’s Cross, Sydney’s one-time Bohemian area.

[Aus](con. 1964-65) B. Thorpe Sex and Thugs and Rock ’n’ Roll 1: King’s Cross [...] The Cross, the ‘Irish Moss’ — or just the ’Irish’ in ‘Steak and Kidney’.