Green’s Dictionary of Slang

blind n.1

[SE blind, any means or place of concealment]

1. in the context of deceit.

(a) [late 18C+] an excuse, a pretence; a person used to fool onlookers, e.g. to disguise a relationship.

(b) [early 19C; 1950s–70s] (US/UK Und.) one who distracts from the activities of a criminal, typically a pickpocket’s assistant.

(c) [20C+] (Und., mainly US) a supposedly legitimate business which in fact masks a criminal one; thus blind man.

2. [late 19C] night-time; thus do a blind, to do a ‘moonlight flit’.

3. [2000s] (US prison) an area of the prison hidden from the authorities’ sight.

In phrases

on the blind

[20C+] (Aus.) at risk, on chance, without any prior information.