The Collaborative International Dictionary
Rearmouse
Rearmouse \Rear"mouse`\, Reremouse \Rere"mouse`\ (-mous`), n. [AS. hr[=e]rem[=u]s; probably fr. hr[=e]ran to agitate, stir (akin to G. r["u]hren, Icel. hr[ae]ra) + m[=u]s mouse.] (Zo["o]l.) The leather-winged bat ( Vespertilio murinus). [Written also reermouse.]
Wiktionary
rearmouse
n. (alternative form of reremouse English)