1. Referring to hatchlings that are naked and blind and dependent on parents for food; such as, altricial birds; as opposed to procotial (active and able to move freely from birth or hatching and requiring little parental care).
2. Designating those animals whose young are helpless and immature at birth, thus requiring prolonged parental care and food provision; such as, songbirds, marsupials, rodents, and carnivores.