Entry 1 sense Webster, 1913 Delusional /dĭl-o͞ozh'-ən-əl/ · De·lu·sion·al · IPA /dɪˈluːʒənəl/ 01 a. Of or pertaining to delusions; as, delusional monomania. 1. Of or pertaining to delusions; as, delusional monomania.