Source : Webster's Revised Unabridged Dictionary (1913)

Semiquadrate \Sem"i*quad`rate\, Semiquartile \Sem"i*quar"tile\,
   n. (Astrol.)
   An aspect of the planets when distant from each other the
   half of a quadrant, or forty-five degrees, or one sign and a
   half. --Hutton.