sem·i·di·ur·nal (sěm
ē-dī-ûr
nəl, sěm
ī-)
adj.► 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.
[TahlilGaran] American Dictionary ▲