[ sem-ee-dahy-ur-nl, sem-ahy- ]
/ ˌsɛm i daɪˈɜr nl, ˌsɛm aɪ- /
pertaining to, consisting of, or accomplished in half a day.
occurring every 12 hours or twice each day.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for semidiurnal
The semidiurnal tidal forces vanish at the Pole and are very small over the entire Arctic Ocean.The North Pole|Robert E. Peary
British Dictionary definitions for semidiurnal
/ (ˌsɛmɪdaɪˈɜːnəl) /
of or continuing during half a day
occurring every 12 hours
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012