Traditionally, a macro lens is one that can focus down to give a life-size image (1x magnification). Most will also focus to infinity. However, more recent Canon macro lenses do not conform to this definition, and would more accurately be described as achieving close-up magnifications (between 0.3x and 1x).
One special lens is the MP-E 65mm f2.8 1-5x Macro. As the name suggests, this only focuses for macro images, from 1x to 5x – there is no infinity focusing.
Some Canon lenses have the word ‘Macro’ inscribed on the side, or an icon of a flower, to depict a close focusing capability.
These are not true macro lenses, as they do not give life-size images.