semordnilap
noun • a word, phrase, or sentence that has the property of forming another word, phrase, or sentence when its letters are reversed.
For example, desserts reversed forms stressed, diaper forms repaid, deliver no evil forms live on reviled, and so on. Two adjacent semordnilaps thus create a palindrome (a string of letters that forms itself when reversed)—i.e., spam maps reversed makes spam maps. The word derives from the reverse spelling of palindromes, making palindromes and semordnilap a semordnilap pair.