Pronunciation: (in sī'tOO, -tyOO, sē'-; Latin.in sit'OO),[key] 1. situated in the original, natural, or existing place or position: The archaeologists were able to date the vase because it was found in situ. 2. Med. a. in place or position; undisturbed.
b. in a localized state or condition: carcinoma in situ.