buck ‧ a ‧ roo /ˌbʌkəˈruː/ BrE AmE noun [countable] American English informal
[ Date: 1800-1900 ; Language: Spanish ; Origin: vaquero 'cowboy' ; influenced by ⇨ ↑ buck 1 ]
a ↑ cowboy – used especially when talking to children
buck ‧ a ‧ roo /ˌbʌkəˈruː/ BrE AmE noun [countable] American English informal
[ Date: 1800-1900 ; Language: Spanish ; Origin: vaquero 'cowboy' ; influenced by ⇨ ↑ buck 1 ]
a ↑ cowboy – used especially when talking to children
Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012