Permanent Wave : A wave (in a fluid) moving with no change in streamline pattern, and which, therefore, is a stationary wave relative to a coordinate system moving with the wave
Intergovernmental Oceanographic Commission IOC technical series 37, Tsunami Glossary (A glossary of terms and acronyms used in the tsunami literature - English), , United Nations Educational, Scientific and Cultural Organization UNESCO, Paris, France 1991. http://unesdoc.unesco.org/images/0008/000885/08853 8eb.pdf, (ND/ Tsunami Sci - Brit) {590}