Definition of in situ in US English:

in situ

adverb & adjective

  • 1In the original place.

    as adverb ‘mosaics and frescoes have been left in situ’
    as adjective ‘a collection of in situ pumping engines’
    • ‘Her mission is preserving populations of native rock grape plants in situ, on site in their native habitat, as part of an ecological preserve.’
    • ‘The archaeologists were able to date the vase because it was found in situ.’
    in position, in situ
    View synonyms
    1. 1.1 In position.
      as adverb ‘her guests were all in situ’
      • ‘These facilities are now in situ with a planned operational date in October.’