Infant

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An infant or baby is the very young offspring of human beings. Infant (from the Latin word infans, meaning 'baby' or 'child'^[1]) is a formal or specialised synonym for the common term baby. The terms may also be used to refer to juveniles of other organisms. A newborn is, in colloquial use, an infant who is only hours, days, or up to one month old. In medical contexts, a newborn or neonate (from Latin, neonatus, newborn) is an infant in the first 28 days after birth;^[2] the term applies to premature, full term, and postmature infants.

Infants born prior to 37 weeks of gestation are called "premature",^[3] those born between 39 and 40 weeks are "full term", those born through 41 weeks are "late term", and anything beyond 42 weeks is considered "post term".^[4]

Before birth, the offspring is called a fetus. The term infant is typically applied to very young children under one year of age; however, definitions may vary and may include children up to two years of age. When a human child learns to walk, they are called a toddler instead.