dénonciateur znamená v Angličtina

whistle-blower [whistle-blowers]▼◼◼◼(one who reports a problem or violation to the authorities)
noun
[UK: ˈwɪs.l̩ ˈbləʊə(r)] [US: ˈwɪs.l̩ ˈbloʊə(r)]

snitch▼◼◻◻(informer, usually one who betrays his group)
noun
[UK: snɪtʃ] [US: ˈsnɪtʃ]

betrayer▼◼◻◻(someone who betrays)
noun
[UK: bɪ.ˈtreɪə(r)] [US: bɪ.ˈtreɪər]