At first, I didn’t think this delightful NY Times story by Andy Newman, about a rescue rat who made it to Broadway, was LH material, but then I got to this passage:
And then Rose did something special. She bruxed, and she boggled. Bruxing is when a rat grinds its incisors together. Boggling, a muscular side effect of bruxing, is when a rat bugs its eyes in and out rapidly, like a possessed vaudeville comic.
They are the ultimate indicators of a relaxed, happy rat.
The OED has only bruxism (entry from 1993), “Involuntary or unconscious grinding or clenching of the teeth, esp. during sleep,” from Greek βρύκειν, βρύχ- ‘to eat greedily, to grind (teeth),’ but a verb brux is an obvious thing to create; as for boggle, the OED has only traditional senses (“To start with fright, to shy as a startled horse,” etc.), but the entry is from 1887. I’m glad to have these new additions to my rat-related vocabulary. And speaking of rat, I hadn’t realized the etymology was so unclear; OED (updated December 2008):
A word inherited from Germanic. Cognate with Old High German rato […]. Compare post-classical Latin ratus, rattus rat (from 12th cent. in British and continental sources […]), Anglo-Norman and Old French rat, masculine (second half of the 12th cent. […]), Old French rate, feminine (second half of the 12th cent. […]), Old Occitan rata (12th cent.) […].
It is uncertain whether the Latin and Romance words are cognate with the Germanic words, or whether they were borrowed from Germanic, or vice versa; in any case the ultimate origin is uncertain; perhaps imitative of the sound of gnawing. None of the Latin and Romance words is attested before the end of the first millennium, and the fact that the German word has not undergone the High German sound shift suggests that the Germanic group is also late (Middle High German ratz, ratze, German regional (chiefly southern) Ratz, Ratze are secondary, perhaps hypocoristic formations). The word was probably spread with the reintroduction of rats to Northern Europe during the Viking Age (for a discussion of the physical evidence compare P. L. Armitage in Antiquity 68 (1994) 231–40).
A derivation < an ablaut variant of the Indo-European base of classical Latin rōdere to gnaw (see rodent adj.) has been suggested, but seems unlikely in the light of the apparently recent introduction of the word.
A suggested derivation of the Romance words < classical Latin rapidus rapid adj. is no longer accepted, as it would only account for the Italian, which for chronological and historical reasons cannot be the single origin of the whole group.