וְיָקְטָ֣ן יָלַ֔ד אֶת־אַלְמוֹדָ֖ד וְאֶת־שָׁ֑לֶף וְאֶת־חֲצַרְמָ֖וֶת וְאֶת־יָֽרַח׃
And Joktan begot Almodad, and Sheleph, and Hazarmaveth, and Jerah;
Rashi on Genesis
חצרמות He was so called (Court of Death) after his city. So is the statement of the Agada (Genesis Rabbah 37:8).
Radak on Genesis
חצרמות, this is one word though it may sound as if it should be two words.
Siftei Chakhamim
He was so called because of his city. [The Aggadah explains that] the people of that city awaited death [מות] every day, because they [were very poor] and ate animal fodder.