decaffeinate Syllabification: (de·caf·fein·ate)Pronunciation: /dēˈkafəˌnāt/Definition of decaffeinate verb [with object] (usually as adjective decaffeinated) remove most or all of the caffeine from (coffee or tea):decaffeinated coffeeDerivatives decaffeinationPronunciation: /dēˌkafəˈnāSHən/ noun decaffeinate in other Oxford dictionaries Definition of decaffeinate in the British & World English dictionary