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.
Medical Definition of Prenatal. Prenatal: Occurring or existing before birth. Prenatal care is the regular health care women should receive from an obstetrician or midwife during pregnancy. Prenatal development is the growth of a single-celled zygote formed by the combination of a sperm and an egg into a baby.