Undergraduates slang. [A humorous deformation from unattached: cf. FOOTER sb.1 3 b, RUGGER2, SOCKER, etc.] An unattached or non-collegiate student at a university having residential colleges.
1889. Durham Univ. Jrnl., 9 Nov., 216. The toshers as they are called in Varsity slangthe term is a corruption of the word unattachedhave been looked down upon in the past.
1891. Duncan, Amer. Girl in Lond., 254. The man being an unattached student, a tosher.
1897. Blackw. Mag., May, 724. A third deemed that the millennium had arrived with the advent to Oxford of the humble tosher.