Locus desperatus
A locus desperatus (Latin for a 'hopeless passage') is a passage in an edition the editor was not able to understand. It may have arisen due to a corruption already present in the archetype. Such passages are marked with a crux in the text (cf. editoral signs). Locus deperditus ('corrupt passage') is a synonym.
An example can be found in Lucretius, De rerum natura VI, 550 (Ernout 1962: 123), where the best manuscripts have the meaningless "dupuis":
Et merito, quoniam plaustris concussa tremescunt
tecta viam propter non magno pondere tota,
nec minus † exultantes dupuis † cumque viai
ferratos utrimque rotarum succutit orbes.
("And with good cause, since buildings beside a road tremble throughout when shaken by a waggon of not such very great weight,
and they rock no less, when † any sharp pebble † on the road jolts up the iron tires of the wheels on both sides"
Trad. Munro, "any sharp pebble" is a conjecture by Munro who reads ... exultant scrupus quicumque viai).
Several emendations for this locus have been proposed besides the one by Munro, among them one by Lachmann, but none has found general acceptance yet.
Reference
– Ernout, Alfred. 1962. Lucrèce: De la nature. Paris: Les Belles Lettres.
– Munro, Hugo A.J. 1866. T. Lucreti Cari de rerum natura libri sex; with notes, translation by H.A.J. Munro. Cambridge: Bell.
In other languages
Latin is used throughout