A bracket or block projecting from the wall of a house, to support a balcony, cornice, etc.; a form of bridge truss, usually supported on a pier, balanced and projecting towards a similar truss on the opposite side of the space bridged, with which it is connected directly or by a girder. Also, cantalever.
- The Winston Simplified Dictionary. By William Dodge Lewis, Edgar Arthur Singer. Published 1919. (noun) (n.) (noun)
( arch.) A wooden or iron block projecting from a wall to bear mouldings, balconies, and the like. The principle has been applied in the construction of bridges to support enormous weights.
- The american dictionary of the english language. By Daniel Lyons. Published 1899. (noun) (n.) (noun)

Usage examples:

Cairo Street boasted 2, 250, 000 visitors, and the Hagenbeck Circus over 2, 000, 000. The chief feature was the Ferris Wheel, described in engineering terms as a cantilever bridge wrought around two enormous bicycle wheels.
- Official Views Of The World's Columbian Exposition by C. D. Arnold H. D. Higinbotham
That was before I succeeded with my- plans for the Michamac cantilever bridge and went to take charge of the construction as resident engineer.
- Out of the Primitive by Robert Ames Bennet
But the man who had crawled out on the shore end of the great cantilever bridge over the Ohio, and who had with his own hands practically set the last rebellious steel girder one hundred feet above the water level, had still some resources left.
- Peter A Novel of Which He is Not the Hero by F. Hopkinson Smith