Henry George Liddell; Robert Scott. "κάλχας (Calchas)". A Greek-English Lexicon. Perseus Digital Library. Liddell and Scott, following the tradition of J.B. Hoffman, relate the name to κάλχη (kalkhe), the purple murex, exactly in the sense of the English mood word "blue". As there is no clear path to an Indo-European root, some suggest a loan word. Hoffman and some others also relate it to Old English gealg or gealh, from an East Germanic *galgaz, "grim", but there is no Indo-European root for that, either. In the most speculative suggestion, the darkness is not blueness but is the color of corroded bronze (kalkhos). Excluded is Old English gealga, "melancholy" from “gallows", with an Indo-European root "branch".
