1300-50; (noun) Middle Englishdeces < Old French < Latindēcessus departure, death, equivalent to dēced-, variant stem of dēcēdere to go away (dē-de- + cēdere to go; see cede) + -tus suffix of v. action, with dt > s; (v.) late Middle Englishdecesen, derivative of the noun
early 14c., from Fr. deces, from L. decessus "death," lit. "departure" (euphemism for mors), from pp. stem of decedere "die," lit. "to go down, depart," from de- "away" + cedere "go" (see cede). Still used with a tinge of euphemism.