Refers to continuously operating, power-driven, moving stairways used as transportation between floors or levels in subways, buildings, and other mass pedestrian areas. An inclined belt for passengers riding on cleats was invented by Jesse W. Reno of the United States in 1891; it was inclined at an angle of 25 degrees, and in the first model, the handrail was stationary. The name "escalator" was first applied to a moving stairway shown at the Paris Exposition of 1900, originally a trademark of the Otis Elevator Company.

Source: Art and Architecture Thesaurus
http://vocab.getty.edu/page/aat/300051244