Portmanteau words mash together the sounds and meanings of two other words, or as Humpty Dumpty tells Alice in "Through the Looking-Glass," they pack two meanings into one word (portmanteau = suitcase or valise). Some portmanteau words paint vivid mental pictures, such as Lewis Carroll's slithy toves who are lithe and slimy at the same time. Others just describe things, such as smog (a blend of smoke and fog), infomercial (a lengthy commercial chock-full of product information), and Reaganomics (the Reagan-era, trickle-down economic policy).