Hypertext Webster Gateway: "semidiurnal"
From Webster's Revised Unabridged Dictionary (1913) (web1913)
Semidiurnal \Sem`i*di*ur"nal\, a.
1. Pertaining to, or accomplished in, half a day, or twelve
hours; occurring twice every day.
2. Pertaining to, or traversed in, six hours, or in half the
time between the rising and setting of a heavenly body;
as, a semidiurnal arc.
Additional Hypertext Webster Gateway Lookup
Gateway by dict@stokkie.net
stock only wrote the gateway and does not have any control over the contents;
see the Webster Gateway FAQ,
and also the Back-end/database links and credits.