What is the meaning of Passerine?

Of or relating to the Passeriformes order of perching birds, which are generally anisodactyl (having three toes pointing forward and one back, which facilitates perching).

Chiefly in the former names of some birds: approximately the size of a sparrow.

Any bird of the order Passeriformes, which comprises more than half of all bird species.

passerine

Source: wiktionary.org