Photomontage is the process (and result) of making a composite photograph by cutting and joining a number of other photographs. The composite picture is sometimes photographed so that the final image is converted back into a seamless photographic print. Today, image-editing software, although not using film, produces similar results. This latter technique is referred to by professionals as "compositing", and in casual usage is often called "photoshopping".
'Group of Royal Family'
by and after John Jabez Edwin Mayall
Prince Albert of Saxe-Coburg-Gotha, Queen Victoria and their children
after John Jabez Edwin Mayall
'The Kings and Queens of England: From the Conquest to Queen Victoria'
by Henry Hering