Definition of tree sparrow
noun
1a Eurasian sparrow with a chocolate brown cap in both sexes, inhabiting agricultural land. - Passer montanus, family Passeridae (or Ploceidae)
2a migratory sparrow-like songbird of the bunting family, breeding on the edge of the North American tundra. - Spizella arborea, family Emberizidae (subfamily Emberizidae)