From BiblePortal Wikipedia

Fausset's Bible Dictionary [1]

("daughter I.E. Worshipper of Jehovah".) Pharaoh's daughter and wife of Mered, a descendant of Judah. Her name shows she was a convert from Egyptian idolatry to Jehovah's worship; and Mered's other wife is distinguished from her, as" Jehudijah" the Jewess. This princess evidently, like Ruth, renounced home, country, and a royal court to take an Israelite husband and to have Israel's God for her God. The marriage probably took place in the wilderness shortly after the Exodus.

Perhaps the disaster of Egypt at the Red Sea led some Egyptians to become proselytes. In Lepsius' Kings' Book, Amenophis II, (in his view) father of the Pharaoh drowned at the Red Sea, has among his children one with the hieroglyphic Amun P or B T H, i.e. beloved of Amun (god of Thebes). On conversion the -Jah added to her name would mark her new religion. (See Egypt , where is stated Canon Cook's view that Thothmes II, much earlier; was the Pharaoh drowned; Amenophis III had a wife not Egyptian in creed, and not of royal birth, named Tel, and her parents Juaa and Tuaa, names not unlike Bithia.)

Hastings' Dictionary of the Bible [2]

Bithiah (‘daughter,’ i.e. worshipper, ‘of J″ [Note: Jahweh.] ’). The daughter of a Pharaoh, who became the wife of Mered, a descendant of Judah (  1 Chronicles 4:18 ). Whether Pharaoh is to be taken here as the Egyp. royal title or as a Heb. proper name, it is difficult to determine.

Holman Bible Dictionary [3]

 1 Chronicles 4:17  1 Chronicles 4:18  1 Chronicles 4:18  1 Chronicles 4:17

Smith's Bible Dictionary [4]

Bithi'ah. (Daughter Of The Lord). Daughter of a Pharaoh, and wife of Mered.  1 Chronicles 4:18. (B.C. about 1491).

Morrish Bible Dictionary [5]

Daughter of some Pharaoh and wife of Mered, a descendant of Judah.  1 Chronicles 4:18 .

Cyclopedia of Biblical, Theological and Ecclesiastical Literature [6]

(Heb. Bithyah', בַּתְיָה , prob. for בִּתאּיָהּ , Daughter [i.e. Worshipper] Of Jehovah; Sept. Βεθθία v. r. Βετθία ), daughter of a Pharaoh, and wife of Mered, a descendant of Judah ( 1 Chronicles 4:18), by whom she had several sons (prob. those enumerated in the latter part of  1 Chronicles 4:17). B.C. cir. 1658. The date of Mered is not positively determined by the genealogy in which his name occurs, some portion of it having apparently been lost. It is probable, however, that he should be referred to the time before the Exodus, or to a period not much later. Pharaoh in this place might be conjectured not to be the Egyptian regal title, but to be or represent a Hebrew name; but the name Bithiah probably implies conversion, and the other wife of Mered seems to be called " the Jewess." Unless we suppose a transposition in the text, or the loss of some of the names of the children of Mered's wives, we must consider the name of Bithiah understood before " she bare Miriam" ( 1 Chronicles 4:17), and the latter part of  1 Chronicles 4:18 and  1 Chronicles 4:19 to be recapitulatory; but the Sept. does not admit any except the second of these conjectures. (See Mered). The Scriptures, as well as the Egyptian monuments, show that the Pharaohs intermarried with foreigners; but such alliances seem to have been contracted with royal families alone. Hence Mered would seem to have been a person of some distinction. It is possible that Bithiah was only an adopted daughter of Pharaoh, or she may have become the wife of Mered in some way through captivity. There is, however, no ground for considering her to have been a concubine; on the contrary, she is shown to be a wife, from her taking precedence of one specially designated as such. (See Hodijah).

International Standard Bible Encyclopedia [7]

bi - thı̄´a ( בּתיה , bithyāh  ; Βεθθιά , Beththiá  ; Codex Vaticanus, Γελιά , Geliá , "daughter of Yah"): The daughter of a Pharaoh who married Mered, a descendant of Judah ( 1 Chronicles 4:18 ). Whether this Pharaoh was an Egyptian king, or whether it was in this case a Hebrew name, it is difficult to say. The name Bithiah seems to designate one who had become converted to the worship of Yahweh, and this would favor the first supposition. If, as the Revised Version (British and American) reads, the other wife of Mered is distinguished as "the Jewess" (instead of the King James Version "Jehudijah"), this supposition would receive further support.