semidiurnal definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
- of, lasting, or performed in half a day
- occurring twice a day, as the tides
semidiurnal definition by American Heritage Dictionary
- Of, relating to, occurring, or performed during half a day.
- Occurring or coming approximately once every 12 hours, as the tides.
- Of or relating to the arc described by a celestial body between its meridian passage and its points of rising or setting.