any of seven North American bird species of the genus Parus, of the family Paridae (order Passeriformes). The name imitates their call notes. Old World members of the genus are called tits, or titmice. Found across North America is the black-capped chickadee (P. atricapillus), 13 cm (5 inches) long, with dark cap and bib. See also tit (titmouse).