Entry 1 sense Webster, 1913 Dietetic /dīˌ-ət-ĕt'-ĭk/ · Di·e·tet·ic · IPA /daɪəˈtɛtɪk/ 01 a. Of or performance to diet, or to the rules for regulating the kind and quantity of food to be eaten. 1. Of or performance to diet, or to the rules for regulating the kind and quantity of food to be eaten.