/ ɪnˈtəʊn; NAmE ɪnˈtoʊn/ verb
( formal ) to say sth in a slow and serious voice without much expression :
[ vn ]
The priest intoned the final prayer.
[also v speech ]
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WORD ORIGIN
late 15th cent. (originally as entone ): from Old French entoner or medieval Latin intonare , from in- into + Latin tonus tone.