Definition of "sonorous"

The Oath is redacted ; pronounced aloud by President Bailly, — and indeed in such a sonorous tone, that the cloud of witnesses, even outdoors, hear it, and bellow response to it.

1837, Thomas Carlyle, “Mercury de Breze”, in Henry Duff Traill, editor, The French Revolution, a History, the Bastille‎, volume 2, New York: Charles Scribner's Sons, The Third Estate, page 162

For this reason the Italian opera seldom sinks into a poorness of language, but, amidst all the meanness and familiarity of the thoughts, has something beautiful and sonorous in the expression.

1761, Joseph Addison, The Works of the Late Right Honorable Joseph Addison, Esq., Birmingham: John Baskerville for J. and R. Tonson, pages 32–33

There is nothing of the artificial Johnsonian balance in his style. It is as often marked by a pregnant brevity as by a sonorous amplitude.

1859 July 25, Edward Everett, “Rufus Choate. Tributes to the Memory of the Hon. Rufus Choate”, in The New York Times, page 2

When the right-away was given, Driver Gibson would give a sonorous blast on Cardean's deep-toned hooter, and amid a flurry of swirling steam the train would move majestically out, with nearly half the city of Carlisle—or so it would appear—as onlookers on the platform.

1945 May and June, Cecil J. Allen, “British Locomotive Practice and Performance”, in Railway Magazine, page 152

Vowels are more sonorous (acoustically powerful) than consonants, and so we perceive them as louder and lasting longer.

2001, Michael Dobrovolsky, “Phonetics: The Sounds of Language”, in William O'Grady, John Archibald, Mark Aronoff, Janie Rees-Miller, editors, Contemporary Linguistics, page 21