n. — diminutive, Ontario, Housing
a building on the property of a summer home that provides additional lodging for guests.
Type: 3. Semantic Change — In Canada, the term is a short form of bunkhouse (see the 2013 quotation) that refers not to workers’ quarters but to summer guest lodging. The term is a Canadianism (see Chart 1), used almost exclusively in Ontario (see Chart 2). Compare also Casselman, s.v. bunkie, who defines the term as "a word used chiefly in Ontario [...] and most often in southern Ontario."
See also COD-2, s.v. "bunkie", which is marked "Cdn (S Ont)".
See also: bunkhouse (meaning 2)
Images:

Chart 1: Internet Domain Search, 8 Oct. 2013 
Chart 2: Regional Domain Search, 5 Nov. 2013