From AMS Glossary
Revision as of 16:44, 20 February 2012 by Perlwikibot
"Long high swells that have increased in height, almost to the breaking point, as they pass over shoals or run in shallow water."
Wiegel, R. L. 1953. Waves, Tides, Currents and Beachers. Glossary of Terms and List of Standard Symbols. Council on Wave Research–The Engineering Foundation.