'mouse-ear' originates from Old English, specifically the words 'mus' meaning 'mouse' and 'ēare' meaning 'ear'.

'mouse-ear' developed as a compound in Middle English combining forms of 'mouse' and 'ear' and eventually became the modern English compound 'mouse-ear'.

Initially it would have literally meant 'the ear of a mouse'; over time it came to be used metaphorically for 'a small, ear-shaped leaf or plant' and for plants named for that shape.