abbreviation of Latin loco citato or locus citatus "in the place (already) cited;" hence, "in the book that has been previously quoted." See locus, cite. In use in English books by 1704.
Entries linking to loc. cit.
locus n.
(plural loci), 1715, "place, spot, locality," from Latin locus "a place, spot; appointed place, position; locality, region, country; degree, rank, order; topic, subject," from Old Latin stlocus, a word of uncertain origin. Used by Latin writers for Greek topos. Mathematical sense by 1750.
cite v.
mid-15c., "to summon, call upon officially," from Old French citer "to summon" (14c.), from Latin citare "to summon, urge, call; put in sudden motion, call forward; rouse, excite," frequentative of ciere "to move, set in motion, stir, rouse, call, invite" from PIE root *keie- "to set in motion, to move to and fro."
Sense of "call forth a passage of writing, quote the words of another" is first attested 1530s. Related: Cited; citing.