The word is unique to this Anglo-Norman gloss, but must be the vernacular equivalent of Latin lutrinus. While the initial l- of the Classical Latin word may be the result of a possible deglutinated definite article (i.e. loterene* became l’oterene; see also the commentary for the entry oterre), the OED suggests an etymology that derives from the Indo-European base of water n., related to Greek ὕδρα (‘water-snake'), Sanskrit udra (‘aquatic animal’), with cognates in Middle Dutch, Middle Low German, Old Icelandic, Danish etc. (see OED otter n.1).