Source : Webster's Revised Unabridged Dictionary (1913)

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 : WordNet®

titmouse
     n : small insectivorous birds [syn: {tit}]
     [also: {titmice} (pl)]