Easton's Bible Dictionary (1897)
Given or gift of God, one of our Lord’s disciples, “of Cana in Galilee” (John 21:2). He was “an Israelite indeed, in whom was no guile” (1:47, 48). His name occurs only in the Gospel of John, who in his list of the disciples never mentions Bartholomew, with whom he has consequently been identified. He was one of those to whom the Lord showed himself alive after his resurrection, at the Sea of Tiberias.
Smith's Bible Dictionary (1863)
(gift of God), a disciple of Jesus Christ, concerning whom, under that name at least, we learn from Scripture little more than his birthplace, Cana of Galilee, (John 21:2) and his simple, truthful character. (John 1:47) The name does not occur in the first three Gospels; but it is commonly believed that Nathanael and Bartholomew are the same person. The evidence for that belief is as follows: St, John who twice mentions Nathanael, never introduces the name of Bartholomew at all.
St. Matthew, (Matthew 10:3) St. Mark, (Mark 3:18) and St. Luke, (Luke 8:14) all speak of Bartholomew but never of Nathanael. If was Philip who first brought Nathanael to Jesus, just as Andrew had brought his brother Simon.
Hastings' Dictionary of the Bible (1898) & Schaff's Bible Dictionary
NATHAN'AEL (gift of God), a native of Cana of Galilee, John 21:2, and an Israelite without guile, as stated by our Lord. John 1:47. He was conducted by Philip (immediately after his call) into the presence of Christ. " Jesus, however, at once convinces him that he is the Messiah by the exhibition of his omniscience, declaring that he had seen Nathanael under the fig tree before ever Philip had called him. Nathanael confesses him to be the Son of God and the King of Israel. The name Nathanael occurs only in John.
For this reason, combined with the fact that John never mentions the name of Bartholomew, it is generally supposed that the two are identical.
Hitchcock's Bible Names (1869)
the gift of God