cove noun
1 a man la16-.
2 a term of address to a man: God, cove I have written to your father and mother saying that I thought you had gone down with the ship. 20-. etymology: OED attested as ‘slang, originally thieves’ cant’ but then suggest that it is perhaps connected with Older Scots cofe ‘a chapman pedlar’; attested by SR and DW note:

Lexicon Balatronicum (1811) defines cove as A man, a fellow, a rogue. The cove has bit the cole. [The rogue has got the money.] Cole being an early slang word for ‘money’

Grose and Egan (1823) attest cove as ‘the master of a house or shop...’

Cited by Canadian Paul Pope (2013) and defined as ‘a friend’.