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 geriatric. 1  1: of or relating to geriatrics or its practice the geriatric department in a hospital a geriatric ward. 2  2: of, relating to, affecting, or being aged individuals the geriatric population geriatric depression treated geriatric animals.