carbaryl Syllabification: (car·ba·ryl)Pronunciation: /ˈkärbəˌril/Definition of carbaryl noun Chemistry a synthetic insecticide used to protect crops and in the treatment of fleas and lice. Alternative name: 1-naphthyl-N-methylcarbamate; chemical formula: C12H11NO2 Origin: mid 20th century: from carbamate + -ylcarbaryl in other Oxford dictionaries Definition of carbaryl in the British & World English dictionary