Between the 1930s and 1970s, employees at Merriam-Webster created a massive “backward index.” It was a card catalog, containing all the words in its dictionary typed backwards. It eventually included around 315,000 index cards. The reason for creating this thing was to allow the company to find words with similar endings. Such as all words ending in ‘ological’. It also helped them create a rhyming dictionary. Computers made the backward index obsolete, but it still sits in the basement of the company’s headquarters.