All 4 Uses

denounce
in
Abraham Lincoln and the Self-Made Myth
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We know that he refused to denounce the Fugitive Slave Law, viciously unfair though it was, even to free Negroes charged as runaways.†
Subsection 4 *
The committee reported proslavery resolutions, presently adopted, which praised the beneficent effects of white civilization upon African natives, cited the wretchedness of emancipated Negroes as proof of the folly of freedom, and denounced abolitionists.†
Subsection 4

denounced = strongly criticized or accused publicly OR (more rarely) informed against someone
On October 4, 1854, at the age of forty-five, Lincoln for the first time in his life denounced slavery in public.†
Subsection 4
He listened to the protests and denunciations of the Radicals and their field agents throughout the country, and politely heard abolition delegations to the White House.†
Subsection 6

denunciations = criticisms or accusations

Definitions:

(1) (denounce)
to strongly criticize or accuse publicly

or more rarely: to inform against someone (turn someone into the authorities)
(2) (meaning too rare to warrant focus)
Much more rarely, denounce can indicate the termination of a treaty or other formal agreement.