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Definition: adjective 1. vertical; upright; in the direction of gravity. 2. (also perpendicular to something) at right angles; forming a right angle with (a particular line or surface). 3. said of a cliff, etc: precipitous; steep.
Source: Chambers 21st Century Dictionary. London: Chambers Harrap, 2001. Credo Reference. Web. 03 September 2012.