1740, Latin, literally "in its (original) place or position," from ablative of situs "site" (see site (n.)).
carcinoma in situ
the archeologists could date the vase because it was in situ
in forma pauperis
in loco parentis
in medias res
in memoriam
in re
in situ
in totidem verbis
in toto
in utero
in vitro
in vivo
