"Baby" is a synonym for baby animals, including human beings. It may also be a colloquial term for children.

Infants (from the Latin language infans, meaning "unable to speak" or "speechless") are more formal or professional synonyms for "infants" (descendants of humans). The term can also be used to refer to the larva of other organisms.

In spoken language, newborn refers to a baby only a few hours, days or less than one month old. In medicine, newborn or newborn (from Latin, newborn, newborn) refers to the baby within the first 28 days after birth; [1] the term is applicable to premature, full-term and premature infants; before birth, the word "fetus" is used. The term "infant" generally applies to children under one year of age; however, the definitions may vary and may include children up to two years of age. When human children learn to walk, they can use the word "infant" instead.