Definition of atom. 1  1a : the smallest particle of an element that can exist either alone or in combination an atom of hydrogenb : the atom considered as a source of vast potential constructive or destructive energy â¦ a largely forgotten legacy of this country's conquest of the atom.
The mountain, a part of the Cascade Range, is a volcano that has not erupted for 2,000 years. It is also the highest mountain in the state of Washington. English explorer George Vancouver named Mount Rainier in honor of another navigator, Peter Rainier. Some people, however, prefer to call the mountain by its Indian name, Mount Tacoma.
Mount Rainier is ranked third of the 128 ultra-prominent mountain peaks of the United States. Mount Rainier has a topographic prominence of 13,211 ft (4,027 m), which is greater than that of K2, the world's second-tallest mountain, at 13,179 ft (4,017 m).