A Palindrome is a word, phrase, number, or other sequence of characters which reads the same backward or forward.
You just need to spell 25 palindromes over the course of the game; they needn't be all in one session. Sometimes you might even get a Quest to spell a certain amount of them, but you can spell them any time for the Achievement.
While it's possible to spell longer palindromes like radar
, it's far easier to concentrate on 3-letter words. Just scan the field for two of the same letter, and then see whether they can be used to make a 3-letter palindrome.
You can also score a free palindrome at the end of any level that contains a gem pile. At the gem pile, just shuffle until the letters for a valid palindrome appear. (This strategy works for several other Achievements as well).
Some 3-letter words that work:
If you discover any valid 3-letter words I missed, let me know and I'll include them in the list.