Imbrication is a fancy word that means the overlapping of edges, such as in scales or tiles. Or shingles, as it turns out. In architectural parlance, imbrication is the use of specially shaped shingles to create a decorative effect. Imbrication is often seen in Victorian homes, especially those built in the Queen Anne style, between about 1880-1900.
The various Victorian house styles are all typified to more or less degree by lots of ornamentation. From the comparatively plain Italianate to the exuberant Queen Anne homes, most Victorian era homes have corbels, fretwork, turned columns, bargeboards, pediments, balustrades, etc. to decorate their exteriors. And why do they? Mainly because of advances in water- and steam-powered lumber mills. Before this time, a skilled carpenter would have to painstakingly carve and cut and turn by hand to produce decorative elements. With the advent of the Industrial Revolution, wooden architectural elements became so easily made and widely used that they could be bought mail-order. (In the 1897 Sears, Roebuck, and Co. Catalog, a fancy glazed front door cost $7.40, and a spindle gable end ornament was $2.00, plus shipping, I presume.)
With the advent of powered mills, cedar shingles could easily be made in uniform widths and with the overlapping edge cut to many different decorative shapes. Combining different shaped shingles together could product even more decorative effects. Painting different rows of shingles contrasting colors adds an additional layer of exuberance.
I took many of these photos walking down a couple blocks of Queen Anne homes in San Jose, CA, just to provide an idea of the wide variety of decorations that can be provided by simple cedar shingles.
Such is the popularity of decorative shingles that they are still made and sold today ready for the next generation of extravagantly and beautifully decorated homes.