► baby a very young child who has not yet learned to walk or talk: The baby was crying upstairs. Let me know as soon as the baby is born.
► newborn (also newborn baby) a baby that has just been born: Newborns spend a lot of time sleeping.
► infant formal a very young baby who cannot talk or walk yet: She held the infant in her arms until he fell asleep.
► toddler a young child who is learning to walk, especially a child from around 18 months to 3 years old: When my son was a toddler, he wouldn’t eat vegetables.
► fetus a baby that is developing in its mother’s body. Used especially by doctors and in science: Alcohol may harm a developing fetus.
► embryo a baby that is in the earliest stages of development inside its mother’s body. Used especially in scientific and medical language: When it is first formed, the embryo is only half a millimeter long.