legal Latin, 1640s in English, literally "in the place of a parent," from loco, ablative of locus "a place" (see locus (n.)) + parentis, genitive of parens "parent" (see parent (n.)).
we had to punish this child in loco parentis
in custodia legis
in extremis
in facie curiae
in fieri
in forma pauperis
in loco parentis
in medias res
in memoriam
in re
in situ
in totidem verbis