'titmouse' originates from Old English, specifically the word 'titmase,' where 'tit' meant 'small' and 'mase' referred to a type of bird.

'titmase' transformed into the Middle English word 'titmous,' and eventually became the modern English word 'titmouse'.

Initially, it referred to any small bird, but over time it evolved to specifically denote birds of the family Paridae.