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.
Sponsored Topics. Rainier is a city in Columbia County, Oregon, United States. The population was 1,687 at the 2000 census. Rainier is located on the south bank of the Columbia River across from Kelso and Longview, Washington. Rainier was founded in 1851 on the south bank of the Columbia River by Charles E. Fox, the town's first postman.