Titmouse \Tit"mouse`\, n.; pl. Titmice. [OE. titemose, titmase; tit small, or a small bird + AS. m[=a]se a kind of small bird; akin to D. mees a titmouse, G. meise, OHG. meisa, Icel. meisingr. The English form has been influenced by the unrelated word mouse. Cf. Tit a small bird.]

(Zo["o]l.) Any one of numerous species of small insectivorous singing birds belonging to Parus and allied genera; -- called also tit, and tomtit.

Note: The blue titmouse (Parus c[oe]ruleus), the marsh titmouse (P. palustris), the crested titmouse (P. cristatus), the great titmouse (P. major), and the long tailed titmouse ([AE]githalos caudatus), are the best-known European species. See Chickadee.

Source: Webster's Revised Unabridged Dictionary (1913)