Friend of God, an honorable person to whom the evangelist Luke addressed his gospel, and the Acts of the Apostles, Luke 1:3; Acts 1:1. We can only say of him, in general, that most probably he was a man of some note, who lived out of Palestine, and had abjured paganism in order to embrace Christianity.
These dictionary topics are from American Tract Society Bible Dictionary published in 1859. Public Domain, copy freely.
Rand, W. W. "Entry for 'THEOPHILUS'". "American Tract Society Bible Dictionary".