adjective: Piercingly loud.
After calliope, a musical instrument having a series of steam whistles played by a keyboard. The instrument was named after Kalliope, the Muse of heroic poetry in Greek mythology, from Greek kalli- (beautiful) + ops (voice). Earliest documented use: 1855.
“Sunday we were doing yardwork when our ears perked to one of the season’s unmistakable aural cues… the calliopean siren’s song of the ice cream truck.”
Check It Out; The News & Observer (North Carolina); Mar 18, 2004.
“Rosalind Russell may have been more ‘bankable’, but didn’t have The Merm’s calliopean vocal cords.”
Ivan M. Lincoln; ‘Gypsy’ Coming to Life Again; The Deseret News (Salt Lake City, Utah); Feb 20, 1994.