LOCO Meaning of LOCO in English lo ‧ co /ˈləʊkəʊ $ ˈloʊkoʊ/ BrE AmE adjective American English informal [ Date: 1800-1900 ; Language: Spanish ] crazy ⇨ ↑ in loco parentis Longman Dictionary of Contemporary English. Longman - Словарь современного английского языка. 2012