Water is a transparent and nearly colorless chemical substance that is the main constituent of Earth's streams, lakes, and oceans, and the fluids of most living organisms. Its chemical formula is H2O, meaning that its molecule contains one oxygen and two hydrogen atoms, that are connected by covalent bonds.
1. recently born; called also neonatal. 2. newborn infant. postmature newborn (post-term newborn) post-term infant. premature newborn (preterm newborn) preterm infant.
An infant is the more formal or specialised synonym for baby, the very young offspring of a human. The term 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, newborn or neonate refers to an infant in the first 28 days after birth; the term applies to premature, full term, and postmature infants; before birth, the term fetus is used. The term infant is typically applied to young children between one month and 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, the term toddler may be used instead.