From BiblePortal Wikipedia

Hastings' Dictionary of the Bible [1]

CHILION and Mahlon were the two sons of Elimelech and Naomi (  Ruth 1:1-2 ). They married women of the Moabites Mahlon marrying Ruth, and Chilion Orpah (  Ruth 4:10 ) and after a sojourn of ten years in Moabite territory died there. Chilion means ‘wasting away.’ Mahlon means ‘sickly.’ Neither of these names occurs elsewhere in the Bible. The two names occur in varying order in   Ruth 1:2;   Ruth 4:9 , so that no conclusion can be drawn as to which was the elder.

Fausset's Bible Dictionary [2]

Orpah's husband, son of Elimelech and Naomi ( Ruth 1:2-5;  Ruth 4:9). An Ephrathite of Bethlehem Judah (formerly Ephrath,  Genesis 35:19).

Morrish Bible Dictionary [3]

Son of Elimelech and Naomi.  Ruth 1:2,5;  Ruth 4:9 .

Holman Bible Dictionary [4]

 Ruth 1:2Ruth

Easton's Bible Dictionary [5]

 Ruth 1:2 4:9

International Standard Bible Encyclopedia [6]

kil´i - on ( כּליון , kilyōn , "pining," "wasting away"): One of the two sons of Elimelech and Naomi, "Mahlon and Chilion, Ephrathites of Bethlehem-judah" (Rth 1:2). With his mother and brother he came into Moab and there both married Moabite women, Orpah being the name of Chilion's wife and Ruth that of the wife of Mahlon (Rth 4:9, Rth 4:10). Both died early and Orpah remained in Moab while Ruth accompanied Naomi back to Bethlehem. When Boaz married Ruth he "bought all that was Elimelech's, and all that was Chilion's, and Mahlon's, of the hand of Naomi" (Rth 4:9).

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [7]

(Hebrews Kilyon ´ , כַּלְיוֹן , Pining; Sept. Χελεών v. r. Χελαιών ), the younger son of Elimelech and Naomi of Bethlehem, and husband of Orpah, Ruth's sister; he died childless in the country of Moab ( Ruth 1:2;  Ruth 4:9). B.C. 1360.