Heteropalindromes (also known as semordnilaps, semi-palindromes, half-palindromes, reversgrams, mynoretehs, reversible anagrams, word reversals, or anadromes) are words which are also words when spelled backwards.
If you are a fan of Word Builder or The Honeycomb, you may want to have a list of heteropalindromes to use in the game.