From BiblePortal Wikipedia

Fausset's Bible Dictionary [1]

(See Noami; Boaz ) Wife of Chilion. (See Chilion .) On her husband's death accompanied Naomi toward Bethlehem a short distance, but, in spite of professions of attachment and tears, she went back to "her people and her gods," and lost the golden opportunity which Ruth embraced of having Israel's God for her God. "Orpah kissed her mother in law, but Ruth clave unto her" ( Ruth 1:14, compare  Proverbs 17:17;  Proverbs 18:24; compare Demas,  2 Timothy 4:10). Orpah's name is now dishonoured, and her seed if she had any is consigned to oblivion. Ruth's Seed - Jesus Christ - is the name at which every knee shall bow ( Philippians 2:10).

Hastings' Dictionary of the Bible [2]

Orpah A Moabitess, sister of Ruth and daughter-in-law of Naomi. When the latter was returning to her own country, Orpah, following Naomi’s advice, elected to go back to her own people and to her god (or gods), while her sister went with her mother-in-law (  Ruth 1:4-14 ).

Morrish Bible Dictionary [3]

Wife of Chilion son of Elimelech. She wept at parting from her mother-in-law, but she returned to Moab when Naomi with Ruth came to Canaan.  Ruth 1:4,14 . She stands in contrast to Ruth, whose faith and trust in the God of Israel were so highly rewarded.

Smith's Bible Dictionary [4]

Or'pah. (A Gazelle). A Moabite woman, wife of Chilion, son of Naomi, and thereby, sister-in-law to Ruth.  Ruth 2:4;  Ruth 2:14. (B.C. 1360).

American Tract Society Bible Dictionary [5]

The Moabites, Naomi's daughter-in-law, who remained with her people and gods, when Ruth followed Naomi and the Lord,  Ruth 1:4-14 . The one was taken and the other left.

Hawker's Poor Man's Concordance And Dictionary [6]

Wife of Chillon, son of Elimelech. ( Ruth 1:4) If from Sarah, the name means nakedness.

Holman Bible Dictionary [7]

 Ruth 1:4-15Ruth

Easton's Bible Dictionary [8]

 Ruth 1:4 4:10

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [9]

(Heb. Orpah', עָרְפָּה , supposed to be transposed for עָפְרָה , A Gazelle; Sept. Ο᾿Ρφά ), a Moabitish woman, wife of Chilion, son of Naomi, and thereby sister-in-law to Ruth. B.C. cir. 1360. On the death of their husbands Orpah accompanied her sister-in-law and her mother-in-law on the road to Bethlehem. But here her resolution failed her. The offer which Naomi made to the two younger women that they should return "each to her own mother's house," after a slight hesitation, she embraced. "Orpah kissed her mother-in-law," and went back "to her people and to her gods," leaving to the unconscious Ruth the glory, which she might have rivalled, of being the mother of the most illustrious house of that or any nation ( Ruth 1:4;  Ruth 1:14). (See Ruth).

International Standard Bible Encyclopedia [10]

ôr´pa ( ערפּה , ‛orpāh  ; for meaning see below): A M oabitess, wife of Mahlon, son of Elimelech and Naomi. Unlike her sister Ruth she returned to her own people after escorting Naomi on her way to Judah (Rth 1:4 ff). Her name is supposed to be derived from the Hebrew word for "neck" (ערף , ‛ōreph ), and so to mean "stiff-necked" because of her turning-back from following her mother-in-law; others take it to mean "gazelle."

Kitto's Popular Cyclopedia of Biblial Literature [11]

Or´pah (fawn), daughter-in-law of Naomi, who remained behind among her kindred in Moab, when Ruth returned with Naomi to Bethlehem [RUTH].