FODMAPs is an acronym that stands for Fermentable Oligo-, Di- and Mono-saccharides, and Polyols. This term was coined by a group of researchers who theorize that foods that contain these forms of carbohydrates exacerbate the symptoms of some digestive disorders, such as irritable bowel syndrome (IBS) and inflammatory bowel disease (IBD).
Looking at FODMAPs more specifically, oligosaccharides are comprised of fructans and galactans; the disaccharides are comprised of lactose; the monsaccharides are comprised of fructose and the polyols are sugar alcohols such as sorbitol, mannitol, xylitol and maltitol. These substances are poorly absorbed by the small intestine and thus it is theorized that they may contribute to digestive difficulties in some people due to the processes of fermentation and/or osmosis.
Essential Reading from Dr. Bolen, Your IBS Guide: