The Collaborative International Dictionary of English v.0.48:

Situs \Si"tus\, n. [L., situation.] (Bot.)
   The method in which the parts of a plant are arranged; also,
   the position of the parts. --Henslow.
   [1913 Webster]

Bouvier's Law Dictionary, Revised 6th Ed (1856):

SITUS. Situation;, location. 5 Pet. R. 524.
     2. Real estate has always a fixed situs, while personal estate has no
such fixed situs; the law rei site regulates real but not the personal
estate. Story, Confl. of Laws, Sec. 379.