A baby is a young human being during the very first months and years of life. Some people refer to three-year-olds as babies, but usually a baby is too young to walk or talk. English speakers often use the pronoun ‘it’ instead of ‘he’ or ‘she’ when talking about a baby.

1. When a baby is born the spine is curved backwards from head to pelvis.
2 …the ghastly non-stop racket that a healthy baby makes when it wants its food.

Infant is a fairly formal word which means the same as baby. Doctors and people writing about how to care for babies often call them infants. Infant can be used before another noun in expressions such as ‘infant health’. You do not normally call a baby an infant, but some writers use the word for stylistic effect or to suggest that the baby is behaving in an unpleasant way.

3. The human infant is uniquely helpless and slow to mature.
4. …infant foods.
5. In half a minute Mrs Taylor was back, carrying the screaming infant in her arms.

A child is a human being at any stage between birth and becoming an adult, especially before becoming a teenager.

6. The teachers adapt their understanding and method to suit the child.
7. Adults find it very hard to realize that young children have no regard for property.

Note that someone’s child is their son or daughter of any age.

. …grown-up children.

• In British English, an infant school is a school for children between the ages of five and seven. In a primary school, the infants are the children between the ages of five and seven.