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.
Of, lasting, or performed in half a day.
Occurring twice a day, as the tides.
Origin of semidiurnal
- semi- +"Ž diurnal