mortal enemy

noun

: someone one hates very much and for a long time

They've been mortal enemies for many years.

Examples of mortal enemy in a Sentence

Recent Examples on the Web

Anyone who tries to teach me will instantly become my mortal enemy. — Grant Brisbee, New York Times, 4 Sep. 2026

The people influenced by their politics overwhelmingly supported and joined the war effort against the Nazis, in part because of a commitment to fight fascism, which was seen as the mortal enemy of the international workers’ movement. — Literary Hub, 12 Aug. 2026

Maybe death at the hands of your mortal enemy doesn’t need to be quick and painless. — Amanda Whiting, Vulture, 29 June 2026

Al Qaeda and Islamic State generally view Shiites as infidels and consider Iran a mortal enemy. — Foreign Correspondent, Los Angeles Times, 1 Mar. 2026