a narrow walkway projecting from a stage into the seating area of a theater; it is used, e. g. by models displaying clothes on it at a fashion show. Called also runway. [WordNet 1.5]
a narrow walkway high in the air to allow workers access to parts of a structure otherwise difficult to reach. Catwalks are located, e.g. above a stage in a theater, between parts of a building, along the side of a bridge, on the outside of a railroad car, on the outside of a large storage tank, etc. [WordNet 1.5]

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OXFORD DICTIONARY

catwalk, n.
1 a narrow footway along a bridge, above a theatre stage, etc.
2 a narrow platform or gangway used in fashion shows etc.

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THESAURUS

catwalk

Bifrost, alameda, bascule bridge, bateau bridge, beaten path, beaten track, berm, bicycle path, boardwalk, bridge, bridle path, cantilever bridge, drawbridge, esplanade, fastwalk, floating bridge, flyover, foot pavement, footbridge, footpath, footway, gangboard, gangplank, gangway, garden path, groove, hiking trail, lift bridge, mall, overbridge, overcrossing, overpass, parade, path, pathway, pontoon bridge, prado, promenade, public walk, rope bridge, run, runway, rut, sidewalk, span, stepping-stone, stepstone, suspension bridge, swing bridge, toll bridge, towing path, towpath, track, trail, trottoir, viaduct, walk, walkway

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