noun (n)

• a high wave (often dangerous) caused by tidal flow (as by colliding tidal currents or in a narrow estuary)(noun.event)

  Synonym:
  aegir, bore, eager, tidal bore
  

  source: wordnet30
• A wave, or two or three successive waves, of great height and violence, at flood tide moving up an estuary or river; -- commonly called the bore. See Bore.(noun)

  source: webster1913