Green’s Dictionary of Slang

1. second-hand, cheap or homemade clothes; also attrib.

[1854		Carroll Free Press (Carrolton, OH) 21 Dec. 1/5: Many young men, who would have otherwise spent their twenty-five years in the bull’s wool of a private, are now basking in the scarlet commissioned coats of British officers].
1926		J. Black You Can’t Win 86: I donned the cheap bullswool suit and threw my good one away.
1928		J. Callahan Man’s Grim Justice in Hamilton Men of the Und. 277: I stole [...] a bull’s wool and oakum shirt.
1930		J. Black ‘A Burglar Looks at Laws and Codes’ in Harper’s Mag. CLX 308: He steps out of prison in his suit of bull’s wool, and squeaky shoes.
1962		Mr. Tully in Dáil Éireann 17 May n.p.: I understand we are now the only civilised nation which has still held on to what is vulgarly known as the bull’s wool uniform.

2. (US black) stolen clothes; also attrib.

1933		Ersine Und. and Prison Sl. 22: bullswool, n. Stolen clothing [...] bullswool thief. One who specializes in robbing clothing stores.
1944		D. Burley Orig. Hbk of Harlem Jive 17: Now the skull was draped in bull’s wool and the banter knew the play.
1949		Monteleone Criminal Sl. (rev. edn) 37: bull’s wool thief A clothing store burglar.
1960, 1975		Wentworth & Flexner DAS.

3. (Aus.) a young man with a mop of bushy hair.