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.

1

1889.  Durham Univ. Jrnl., 9 Nov., 216. The ‘toshers’ as they are called in ’Varsity slang—the term is a corruption of the word ‘unattached’—have been looked down upon in the past.

2

1891.  Duncan, Amer. Girl in Lond., 254. The man … being an unattached student, a ‘tosher.’

3

1897.  Blackw. Mag., May, 724. A third deemed that the millennium had arrived with the advent to Oxford of the humble ‘tosher.’

4