1719, alteration of salva
(1591) "simultaneous discharge of guns," from It. salva
"salute, volley" (cf. Fr. salve,
from It.), from L. salve
"hail!," lit. "be in good health!," the usual Roman greeting, regarded as imperative of salvere
"to be in good health," but prop. voc. of salvus
"healthy" (see safe
(adj.)). The notion is of important visitors greeted with a volley of gunfire into the air.