ThamesPronunciation: /tɛmz/Translate Thames | into French | into German | into Italian | into Spanish Definition of Thames a river of southern England, flowing 338 km (210 miles) eastwards from the Cotswolds in Gloucestershire through London to the North Sea. a shipping forecast area covering the southernmost part of the North Sea, roughly as far north as the latitude of northern Norfolk. Thames in other Oxford dictionaries Definition of Thames in the US English dictionary