Anciently, a page; a knight or a gentleman's attendant; now a low fellow; a scoundrel; a rascal.
- Nuttall's Standard dictionary of the English language. By Nuttall, P.Austin. Published 1914. (noun) (n.) (noun)
Formerly, a servant, footman, or page; a scoundrel.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (noun) (n.) (noun)
A servant or footman; a scoundrel; a rascal.
- Etymological and pronouncing dictionary of the English language. By Stormonth, James, Phelp, P. H. Published 1874. (noun) (n.) (noun)
A footman: a low fellow: a scoundrel.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (noun) (n.) (noun)
A footman; servant; knave.
- The Clarendon dictionary. By William Hand Browne, Samuel Stehman Haldeman. Published 1894. (noun) (n.) (noun)

Usage examples:

You don't suppose that I am joking with you," he went on as the varlet looked at him suspiciously, " when I should likely be whipped for my pains.
- At Agincourt by G. A. Henty
She has a favourite page, to attend upon her person; a handsome boy of about twelve years of age, but a mischievous varlet very much spoiled, and in a fair way to be good for nothing.
- Bracebridge Hall, or The Humorists by Washington Irving
What means the varlet
- The Comedies of Terence by Publius Terentius Afer