Merriam-Webster may be one of the most respected names in the dictionary business, but the giant isn’t always perfect. In 1934, the company released an edition of Webster’s New International Dictionary including the word “dord,” which was defined as a synonym for “density.” But no such term actually existed within the physics and chemistry lexicon.
This “ghost word” came about after someone at Webster misinterpreted a piece of paper sent in by the company’s chemistry editor. It read, “D or d, cont./density.” What the editor meant to convey is that “density” should be added to the list of words that can be abbreviated with “D.” Dord was somehow assigned a pronunciation guide (dôrd), it slipped past the proofreaders, and it ended up on page 771 of the esteemed catalog of English vocabulary.
Inevitable future line of IKEA wastepaper baskets notwithstanding, “dord” is no longer masquerading as a real word. An editor identified the impostor in 1939, but it wasn’t fully banished from all G & C Merriam Company dictionaries until 1947.
One of the most interesting things I've heard about dictionary's and the way they protect their information from copyright (a competing dictionary copying their definitions to cut corners), is that they will intentionally create words that don't exist with definitions in order to sue any competitors using their definitions. I cant find any examples of the words they made on google because I cant search specifically enough for what I want lol.