English Regional, South-Western, Midlands, Welsh English rare, archaic
A bat.
Origin
Old English; earliest use found in Glosses to Proverbs of Solomon. Apparently from a first element of uncertain origin + mouse, perhaps as alteration of Old English hrēaðemūs.
Definition of rearmouse in US English:
rearmouse
nounˈrɪəmaʊs
English Regional, South-Western, Midlands, Welsh English rare, archaic
A bat.
Origin
Old English; earliest use found in Glosses to Proverbs of Solomon. Apparently from a first element of uncertain origin + mouse, perhaps as alteration of Old English hrēaðemūs.