1. an ancient city in Bithynia; founded in the 4th century BC and flourished under the Romans; the Nicene Creed was adopted there in 325 • Derivationally related forms: Nicaean • Instance Hypernyms: city, metropolis, urban center • Part Holonyms: Bithynia 2. the seventh ecumenical council in 787 which refuted iconoclasm and regulated the veneration of holy images • Syn: Second Council of Nicaea • Hypernyms: ecumenical council 3. the first ecumenical council in 325 which produced the wording of the Nicene Creed and condemned the heresy of Arianism • Syn: First Council of Nicaea • Hypernyms: ecumenical council