From BiblePortal Wikipedia

Fausset's Bible Dictionary [1]

Saul's oldest daughter ( 1 Samuel 14:49). According to promise to the conqueror of Goliath, Saul betrothed Merab to David ( 1 Samuel 17:25;  1 Samuel 18:17), but with the secret design of inciting him thereby to expose himself to be slain by the Philistines. At the time when Merab should have been given to him Saul gave her to Adriel the Meholathite. Her five sons subsequently were crucified to Jehovah by the Gibeonites among the seven, for Saul's bloodthirsty zeal against them ( 2 Samuel 21:9). See  Exodus 34:7; how Saul's sin recoiled on himself and his! "Michal" is a copyist's error for Merab ( 2 Samuel 21:8); reading "Michal" we must understand "brought up," not gave birth to (compare  Ruth 4:16-17). (See Michal .)

Smith's Bible Dictionary [2]

Me'rab. (Increase). Eldest daughter of King Saul.  1 Samuel 14:49. In accordance with the promise which he made, before the engagement with Goliath,  1 Samuel 17:25, Saul betrothed Merab to David.  1 Samuel 18:17. Before the marriage, Merab's younger sister, Michal, had displayed her attachment for David, and Merab was, then, married to Adriel, the Meholathite, to whom she bore five sons.  2 Samuel 21:8.

American Tract Society Bible Dictionary [3]

The eldest daughter of king Saul, was promised to David in marriage, in reward for his victory over Goliath; but was given to Adriel, son of Barzillai the Meholathite,  1 Samuel 14:49   18:17,19 . Merab had five sons by him, who were delivered to the Gibeonites, and hanged before the Lord,  2 Samuel 21:8,9 . The text intimates that the five men delivered to the Gibeonites were sons of Michal; but see Adriel .

Hastings' Dictionary of the Bible [4]

MERAB. The elder daughter of Saul, promised to the slayer of Goliath (  1 Samuel 17:25 ), and then to David personally as a reward for prowess against the Philistines (  1 Samuel 18:17 ), but given as wife to Adriel the Meholathite. In   2 Samuel 21:8 Michal , whose sons are said to have been given over to satisfy the Gibeonites, is probably a scribal error for Merab.

W. F. Boyd.

People's Dictionary of the Bible [5]

Merab ( Mç'R Ăb ), Increase. The eldest daughter of Saul,  1 Samuel 14:49, promised to David, but given to Adriel in marriage.  1 Samuel 18:17;  1 Samuel 18:19.

Holman Bible Dictionary [6]

 1 Samuel 14:49 1 Samuel 17:25 1 Samuel 18:17-19 2 Samuel 21:8

Morrish Bible Dictionary [7]

Eldest daughter of Saul: she was promised to David, but was given to Adriel the Meholathite.  1 Samuel 14:49;  1 Samuel 18:17,19 . See ADRIEL.

Hawker's Poor Man's Concordance And Dictionary [8]

Daughter of Saul, ( 1 Samuel 14:49) Her name is taken from Rabah, mistress.

Easton's Bible Dictionary [9]

 1 Samuel 14:49 2 Samuel 21:8

International Standard Bible Encyclopedia [10]

mē´rab ( מרב , mērabh "increase"; Μερόβ , Merób ): The elder daughter of Saul (  1 Samuel 14:49 ), promised, though not by name, to the man who should slay the Philistine Goliath ( 1 Samuel 17:25 ). David did this and was afterward taken by Saul to court ( 1 Samuel 18:2 ), where he was detained in great honor. Merab was not, however, given to him as quickly as the incident would lead one to expect, and the sequel showed some unwillingness on the part of some persons in the contract to complete the promise. The adulation of the crowd who met David on his return from Philistine warfare and gave him a more favorable ascription than to Saul ( 1 Samuel 18:6-16 ) awoke the angry jealousy of Saul. He "eyed David from that day and forward" ( 1 Samuel 18:9 ). Twice David had to "avoid" the "evil spirit" in Saul ( 1 Samuel 18:11 ). Saul also feared David ( 1 Samuel 18:12 ), and this led him to incite the youth to more dangerous deeds of valor against the Philistines by a renewed promise of Merab. He will have David's life, but rather by the hand of the Philistines than his own ( 1 Samuel 18:17 ). Merab was to be the bait. But now another element complicated matters - M ichal's love for David ( 1 Samuel 18:20 ), which may have been the retarding factor from the first. At any rate Merab is finally given to Adriel the Meholathite ( 1 Samuel 18:19 ). The passage in  2 Samuel 21:8 doubtless contains an error - M ichal's name occurring for that of her sister Merab - though the Septuagint, Josephus, and a consistent Hebrew text all perpetuate it, as well as the concise meaning of the Hebrew word Yāladh , which is a physiological word for bearing children, and cannot be translated "brought up." A T argum explanation reads: "The 5 sons of Merab (which Michal, Saul's daughter brought up) which she bare," etc. Another suggestion reads the word "sister" after Michal in the possessive case, leaving the text otherwise as it stands. It is possible that Merab died comparatively young, and that her children were left in the care of their aunt, especially when it is said she herself had none ( 2 Samuel 6:23 ). The simplest explanation is to assume a scribal error, with the suggestion referred to as a possible explanation of it. The lonely Michal ( 2 Samuel 6:20-23 ) became so identified with her (deceased) sister's children that they became, in a sense, hers.

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [11]

(Hebrews Merlab', מֵרִב , Increase ; Sept. Μερόβ and Μερώβ ; Josephus Μερόβη , Ant. 6:6, 5), the eldest of the two daughters of king Saul (doubtless by his wife Ahinoam), and possibly the eldest child ( 1 Samuel 14:49). She first appears (BC. cir. 1062) after the victory over Goliath and the Philistines, when David had become an inmate in Saul's house ( 1 Samuel 18:2), and immediately after the commencement of his friendship with Jonathan. In accordance with the promise which he made before the engagement with Goliath ( 1 Samuel 17:25), Saul betrothed Merab to David ( 1 Samuel 18:17), but it is evidently implied that one object of thus rewarding his valor was to incite him to further feats, which might at last lead to his death by the Philistines. David's hesitation looks as if he did not much value the honor, although his language in  1 Samuel 18:18 may be only an Oriental form of self-depreciation (comp.  1 Samuel 18:23;  1 Samuel 25:42;  2 Samuel 9:8); at any rate before the marriage Merab's younger sister Michal had displayed her attachment for David, and Merab was then married to Adriel the Meholathite, who seems to have been one of the wealthy sheiks of the eastern part of Palestine, with whom the house of Saul always maintained an alliance. To Adriei she bore five sons, who formed five of the seven members of the house of Saul who were given up to the Gibeonites by David, and by them impaled as a propitiation to Jehovah on the sacred hill of Gibeah ( 2 Samuel 21:8). (See Rizpah).

The Authorized Version of this passage is an accommodation, rendering יָלְדָה , "she brought up," although it has "she bare" for the same Hebrew word in the previous part of the verse. The Hebrew text has "the five sons of Michal, daughter of Saul, which she bare to Adriel," and this is followed in the Sept. and Vulgate. The Targum explains the discrepancy thus: "The five sons of Merab (which Michal, Saul's daughter, brought up) which she bare," etc. The Peshito substitutes Merab (in the present state of the text " Nodob") for Michal. J. H. Michaelis, in his Hebrew Bible ( 2 Samuel 21:10), suggests that there were two daughters of Saul named Michal, as there were two Elishamas and two Eliphalets among David's sons. Probably the most feasible solution of the difficulty is that "Michal" is the mistake of a transcriber for "Merab;" but, if so, it is manifet from the agreement of the versions and of Josephus (Ant vii. 4,30) with the present text, that the error is one of very ancient date. (See Michal).

Kitto's Popular Cyclopedia of Biblial Literature [12]

Me´rab (Increase) eldest daughter of king Saul, who was promised in marriage to David; but when the time fixed for their union approached, she was, to the surprise of all Israel bestowed in marriage upon an unknown personage named Adriel . By him she had six sons, who were among those of the house of Saul that were given up to the Gibeonites, who put them to death in expiation for the wrongs they had sustained from their grandfather.