Added 9 October 2026 istanbul noun Categories: PlacesUncommon Words noun ! Definition from WordNet 3.1, Princeton University. More about istanbul at Wordnik → Where our words come from → The largest city and former capital of Turkey; rebuilt on the site of ancient Byzantium by Constantine I in the fourth century; renamed Constantinople by Constantine who made it the capital of the Byzantine Empire; now the seat of the Eastern Orthodox Church. Related Words: constantinoplestamboulstambulturkishankaraturkeybyzantiumbyzantionmiklagardistambultsargradizmir Back to today's word