Dogs that won't hunt and Old English ghost words.

Medieval writing errors and modern misreadings can, alone or together, add spurious words to the Old English lexicon - 'ghost words' that would have been unknown to an Old English speaker. I recently happened across an example in the Antwerp-London glossaries, where an entry in modern edition reads 'Inutilis canis. hrodhhund'.(1)

A great deal of philological knowledge has gone into supporting the reading: if the element hrodh is a variant of rodh (cognate with rydhdhe), hrodhhund therefore equals rodhhund ('mastiff'). Inutilis equals rusticus, so therefore inutilis canis is the same as rusticus canis, which equals molossus, a Virgilian term (and frequent glossary entry) …