diesis

noun

di·​esis ˈdī-ə-səs 

plural dieses ˈdī-ə-ˌsēz 

: double dagger

Word History

Etymology

probably from Italian, sharp (in music), symbol for a sharp, from Medieval Latin, quarter tone, from Latin, from Greek, from diiēnai to send through, from dia- + hienai to send — more at jet

First Known Use

circa 1706, in the meaning defined above