Source : Webster's Revised Unabridged Dictionary (1913)

In situ \In` si"tu\ [L.]
   In its natural position or place; -- said of a rock or
   fossil, when found in the situation in which it was
   originally formed or deposited.

In situ \In si"tu\ [L.]
   In its natural or original position or place; in position; --
   said specif., in geology, of a rock, soil, or fossil, when in
   the situation in which it was originally formed or deposited.

Source : WordNet®

in situ
     adv : in the original or natural place or site; "carcinoma in
           situ"; "the archeologists left the pottery in place"
           [syn: {in place}]