🔼The name Mahlon in the Bible
There's only one Mahlon in the Bible. He is the brother of Chilion, and they are the two sons of Elimelech and Naomi of Bethlehem (Ruth 1:2). A famine forces Elimelech to move his family to Moab, but it's not clear from the story if things are better over there. Elimelech dies, and the two sons marry Moabite women: Chilion marries Orpah and Mahlon marries Ruth. Ten years later, Mahlon and Chilion too die.
Orpah moves back to her people but Ruth travels with Naomi to Bethlehem. There she meets Boaz, who marries her evoking the levirate law, which stipulates that if a man dies childless, his brother or close relative should marry his widow and bring forth children in his name. Ruth and Boaz become the great-grandparents of king David and the ancestors of Jesus Christ, but according to the levirate law, the lineage should be traced through Mahlon and not Boaz.
🔼Etymology of the name Mahlon
The name Mahlon appears to be derived from the verb חלה (hala), meaning to be weak, sick or wounded:
Our name ends with the familiar waw-nun-extension, which creates a localized or personified manifestation of the verb. The name Mahlon literally means Man Of Weakness.
For a meaning of the name Mahlon, NOBSE Study Bible Name List reads Sickly. Alfred Jones (Dictionary of Old Testament Proper Names) takes the waw-nun-extension to be an "intensitive termination" and translates our name with Great Infirmity. BDB Theological Dictionary does not translate our name and also doesn't list it under the verb חלה. Whether that is because BDB disputes that Mahlon's root is חלה is unclear.