Green’s Dictionary of Slang

one who works hard at their books.

1788		Trifler No. 5 56: How erroneous my supposition had been; the diligence exercised in improving my mental abilities, brought upon me the almost indelible stigma of a Muz .
1807		in Spirit of Public Journals (1809) XII 305: I often wish you had been with us, though we do quiz you for a reading muz .
1899		W.K.R. Bedford Outcomes Old Oxford 86: I don’t mind memoirs, but I hate a muzz (a bookworm).