Focal length multiplier
From The Glossary of Digital Photography
A term used with digital cameras that have sensor sizes smaller than 35mm to indicate what the 35mm equivalent size of a particular lens would be. Thus, if a digital camera has a 1.5 focal length multiplier, a 50 mm lens used on that digital camera would be equal to a 75 mm lens (50 x 1.5 = 75) used on a 35mm camera. Full-frame digital cameras have a focal length multiplier of 1.0, which means that a lens used on that digital camera would have approximately the same field of view of a 35mm camera.
