Green’s Dictionary of Slang

1. a horse.

1914		T. Hampson diary 25 Aug. 🌐 The recognised distance for heavy draught animals to cover in a day is 14 miles, so our hairies had done pretty well today.
1916		‘New Church’ Times 17 Apr. (2006) 53/1: Groom, turn the hairy out to grass!

2. (Scot., a woman, esp. Glasgow) a poor woman [the premise is that a wealthier woman would wear a hat and hide her hair].

1935		(con. 1920s) McArthur & Long No Mean City 31: She was, quite definitely, ‘one of the hairy’ – a hatless slum girl.
1962		B. McGhee Cut and Run (1963) 10: The Glasgow street-corner girl is sometimes known [...] as a ... HAIRY ...
1976		P. Theroux Family Arsenal 29: That hairy over their pulling pints.
1998		I. Welsh Filth 150: That wee hairy last night, I should have fucked her up the arse.
2012		(con. 1980s) I. Welsh Skagboys 295: Could pimp her oot easy. Like some ay they wee hairies around here.

3. a long-haired individual, a hippie.

1970

Oshkosh Northwestern (WI) 18 Apr. 18/4: The skinhead families hate hippies and Hell’s Angels whom they call ‘hairies’ and ‘greasers’.