murcus.

Uncertain. The term is perhaps connected with marceō (“to be soaked”), itself from Proto-Indo-European *merk-. However, according to the linguist Nicholas Zair, it is most likely that the Latin verb showcases a development of Proto-Indo-European *mr̥k- to Proto-Italic *mork-, which then unrounded to *ma-. If this is accepted, then—according to Zair—the form murcus cannot be directly derived from Proto-Indo-European *mr̥k-o- or *mork-o-, and must instead have been borrowed from some other Indo-European substrate language where the unrounding never took place. De Vaan, however, suggests that a zero-grade Proto-Indo-European form *mr̥k- would have instead vocalized as Proto-Italic *mark-, whence marceō, whereas the o-grade would have regularly produced forms such as murcidus. Alternatively, the term may have emerged as back-formation from murcidus. The Hesychius hapax Ancient Greek μύρκος (múrkos), μυρικᾶς (murikâs, “mute, dumb”), transmitted as being used in Syracuse, is deemed by Oikonomos, Ernout/Meillet and Beekes borrowed from Latin.