caprolactam Syllabification: (cap·ro·lac·tam)Pronunciation: /ˌkaprōˈlakˌtam/Definition of caprolactam noun Chemistry a synthetic crystalline compound that is an intermediate in nylon manufacture. A lactam; chemical formula: C6H11NO Origin: 1940s: from caproic acid + lactamcaprolactam in other Oxford dictionaries Definition of caprolactam in the British & World English dictionary