1. [late 18C+] (US) a Canadian, esp. a resident of Nova Scotia [SE bluenose, a variety of potato native to Nova Scotia, but note late 17C Scot. bluenose, a Scot. Presbyterian and the stereotyped New England Yankee, seen as blue-nosed adj. (2), thus the northern nose is blue with chilly disapproval].
2. [mid-19C] (US) a Northerner, esp. a New Englander.
3. a Nova Scotian ship, or a member of its crew.
4. [late 19C+] (US) a dedicated, fanatical puritan, almost invariably a teetotaller; also attrib. [orig. an aristocrat (who had ‘blue blood’), bluenoses passed the repressive ‘blue laws’ that restricted the morals of many states ? + the opposite of the drunk, who boasts a conspicuously red nose].
5. [1930s+] someone who sees themselves as superior to their neighbours.
6. attrib. use of sense 4.