"to intone, recite in a singing voice," 1795, from Medieval Latin intonatus, past participle of intonare "sing according to tone" (see intone). Compare Italian intonare, French entonner. Related: Intonated; intonating.
"to thunder, rumble," 1620s, from past participle stem of Latin intonare "to thunder, thunder forth," from in- (from PIE root *en "in") + tonare "to thunder" (see thunder (n.)). Related: Intonated; intonating.