From BiblePortal Wikipedia

Fausset's Bible Dictionary [1]

("vain, empty, son of Zipper".) Not hereditary king, but imposed on Moab by Sihon. (See Balaam ; HUR (2).) His employment of Balaam to curse Israel was near the close of Israel's journeying. His knowing as to the seer in Mesopotamia would imply a circulation of intelligence, great considering the times. Moab's descent from Lot, originally of Mesopotamia; also the merchant caravans passing across the deserts; also the advanced civilization of Moab in letters, proved by the Moabite stone some centuries later: all make it intelligible. Finding Israel "too mighty" for him ( Numbers 22:6), and his hope of prevailing by Balaam's enchantments being disappointed, he let them alone thenceforth. His "warring against Israel" ( Joshua 24:9-10) consisted not in "fighting," which is denied in  Judges 11:25, but in hiring Balak against them.

Hastings' Dictionary of the New Testament [2]

Balak is named in  Revelation 2:14 along with Balaam. Like Balaam ( q.v. [Note: quod vide, which see.] ), Balak is to be regarded here as a typical figure. The former teaches doctrine which is false in itself, corrupt in its motive, and immoral in its fruits; while Balak is, as in the OT, the heathen power which thrusts Balaam’s sorceries on the faithful. It is difficult to resist the conclusion that, if Balaam is the teacher of Gnosticism, Balak is the Roman power which has adopted syncretism and seeks to compel the Christians to adopt its ways also, and so makes them fall into the corruptions attendant on pagan worship.

W. F. Cobb.

American Tract Society Bible Dictionary [3]

King of Moab, when the Israelites were drawing near the promised land. He was filled with terror lest they should attack and destroy him, as they had Sihon and Og, and implored the soothsayer Balaam to come and curse them. His fears and his devices were both in vain,  Deuteronomy 2:9 . See Balaam . He found he had nothing to fear from Israel if at peace with them, and nothing to hope if at war with them.

Hawker's Poor Man's Concordance And Dictionary [4]

The Prince of Moab and Midian: the son of Zippor. We have his history,  Numbers 22:1-41 and following chapters. His name signifies, wasting, from Lakak, to lick up, and the prefix Beth, with.

See Balaam

Smith's Bible Dictionary [5]

Ba'lak. (Spoiler). Son of Zippor, king of the Moabites, who hired Balaam to curse the Israelites; but his designs were frustrated in the manner recorded in  Numbers 22:24. (B.C. 1451).

Hastings' Dictionary of the Bible [6]

BALAK . The king of Moab who hired Balaam,   Numbers 22:1-41;   Numbers 23:1-30;   Numbers 24:1-25 . See Balaam.

Easton's Bible Dictionary [7]

 Numbers 22:2,4 Joshua 24:9

Holman Bible Dictionary [8]

 Numbers 22:2Balaam

People's Dictionary of the Bible [9]

Balak. See Balaam.

Kitto's Popular Cyclopedia of Biblial Literature [10]

Ba´lak (emptier, spoiler), son of Zippor, and king of the Moabites ( Numbers 22:2;  Numbers 22:4), who was so terrified at the approach of the victorious army of the Israelites, who in their passage through the desert had encamped near the confines of his territory, that he applied to Balaam, who was then reputed to possess great influence with the higher spirits, to curse them. From  Judges 11:25, it is clear that Balak was so certain of the fulfillment of Balaam's blessing, 'blessed is he that blesseth thee, and cursed is he that curseth thee' ( Numbers 24:9), that he never afterwards made the least military attempt to oppose the Israelites (comp.  Micah 6:5;  Revelation 2:14).

International Standard Bible Encyclopedia [11]

bā´lak בּלק , bālāḳ , "devastator" or "one who lays waste"): Mentioned in connection with the story of Balaam/Balak (Nu 22 through 24; compare  Joshua 24:9;  Judges 11:25;  Micah 6:5;  Revelation 2:14 ). He was the king of Moab who hired Balaam to pronounce a curse on the Israelites. See Balaam .