A palindrome is a word or phrase that reads the same backwards and forwards. Some examples are the words “repaper” and “aibohphobia” (which is the fear of palindromes). There are also the phrases “madam, I’m Adam,” “a man, a plan, a canal: Panama,” and “was it a car or a cat I saw?”
There’s another sort of similar thing; a word that is a different word when reversed. “Desserts” backwards is “stressed,” “diaper” is “repaid,” “live” is “evil,” and so forth. A word or phrase like that is an “anadrome,” “antigram,” or “semordnilap” (that last one is “palindromes” backwards). “Palindrome” comes from Greek roots that meant “running back again,” and has been around in English since at least 1637, when Benjamin Jonson included “Had I…weav’d fiftie tomes Of Logogriphes, or curious Palindromes” in The Workes of Ben Jonson. And I suppose we should expect “palindrome” to remain in use until about 7361.
“Semordnilap” is nowhere near as old or as common as “palindrome,” and in fact the whole idea of word for a word that’s a different word backwards seems to be pretty recent. You can find it used here and there, though, even in ostensibly serious publications like Nicole Shukin’s 2009 Animal Capital: Rendering Life in Biopolitical Times: “Derrida particularly favors the figure of a “headstrong dog,” possibly because dog, a semordnilap for god, helps him to configure an immanent versus transcendent ontology.” You can tell that this is a serious publication because of sentences like this: “In the author’s view, the Maoist kepu project failed wherever it disregarded the complexity, centrality, and irreducibility of human identity, and through post-Mao discussion of Peking Man, Yeren, and others, are in many ways confirmations of Mao’s worst fears, they are also poignantly authentic manifestations of his most populist dreams.”
That sentence, of course, is not a palindrome because it doesn’t read the same backwards and forwards. But it could conceivably be a semordnilap, because while it’s difficult to tell quite what it means in the forward direction, it definitely means something different read from end to beginning.
Finding words and phrases that still mean something (that is, appear in a dictionary list) in both directions is, of course, an obvious and pretty straightforward job for a computer. And palindromes and semordnilaps are just the sorts of things that computer programmers would enjoy playing around with, so as you’d expect, there are any number of lists posted on the web. The word “semordnilap” was probably first used by Dimitri Borgmann. Borgmann became known in 1958 when he won the TV game show It’s In The Name, which featured some sort of word game. Possibly because of his win, he started writing the Line o’ Type or Two column in the Chicago Tribune. By about 1964 he was fairly well known as “the country’s leading authority on word play” (according to Newsweek magazine), and started to write books as well, including Language on Vacation: An Olio of Orthographic Oddities. Based on that book, not to mention his existing reputation, he got at least one contract to come up with inventive brand names for products — the most famous one, which you might have heard of, was Exxon.
Borgmann also published under fanciful pen names such as Ramona J. Quincunx and Prof. Merlin X. Houdini. That might be a hint that he was a somewhat eccentric fellow. A stronger hint is that he was extremely reclusive, and none of the people he worked with to publish his books and columns ever met him in person. Reportedly he preferred the windows of his house to be boarded up or draped, and he didn’t allow any mirrors in the place.
Not only that, but in the late 1970s he founded the Divine Immortality Church and placed ads in major magazines like The Atlantic trying to sell divinity degrees and ordainment certificates. It’s not clear how serious he was about this; it could have been some odd sort of joke. But according to a biographical article in the Journal of Recreational Linguistics (another ostensibly serious publication), at least one hundred people actually joined the Divine Immortality Church. To most people, though, it was either a joke or a scam, and a good subject for a bit of wordplay of their own. They called it the Devine Immorality Church.