Numbers 5:18הַמָּרִים
After the priest has the woman stand before the LORD, he is to let down her hair and place in her hands the grain offering of memorial, which is the grain offering for jealousy. The priest is to hold the bitter water that brings a curse.
1 Samuel 15:32מַר
Then Samuel said, “Bring me Agag king of the Amalekites.” Agag came to him cheerfully, for he thought, “Surely the bitterness of death is past.”
Job 7:11בְּמַר
Therefore I will not restrain my mouth; I will speak in the anguish of my spirit; I will complain in the bitterness of my soul.
Proverbs 5:4מָרָה
in the end she is bitter as wormwood, sharp as a double-edged sword.
Isaiah 5:20מַר
Woe to those who call evil good and good evil, who turn darkness to light and light to darkness, who replace bitter with sweet and sweet with bitter.
Ezekiel 3:14מַר
So the Spirit lifted me up and took me away, and I went in bitterness and in the anger of my spirit, with the strong hand of the LORD upon me.

Brown-Driver-Briggs

מַר adj. and subst. bitter, bitterness

Sources: Brown-Driver-Briggs (1906, public domain) from the Open Scriptures Hebrew Lexicon (CC BY 4.0), glosses from STEPBible TBESH (CC BY 4.0); STEPBible TAHOT (Hebrew Bible, Leningrad Codex, CC BY 4.0); the Berean Standard Bible (public domain). Reformatted by Word Study, wording unchanged. All sources and licenses.