Entry 1 sense Webster, 1913 Regicidal /(rĕj"ĭ*sī`dal)/ · Reg·i·ci·dal · IPA 01 a. Pertaining to regicide, or to one committing it; having the nature of, or resembling, regicide. 1. Pertaining to regicide, or to one committing it; having the nature of, or resembling, regicide.