A large district in the north of Asia Minor, bordering on the Black Sea. Paul and Timotheus attempted to go into Bithynia, but the Spirit suffered them not. Acts 16:7 . Peter addressed his first Epistle to those of the dispersion of Bithynia, etc. 1 Peter 1:1 . It was then a Roman province: it is now called Kastamuni, a part of Turkey in Asia.