A palindrome is a word, phrase, number, or other sequence of units that may be read the same way in either direction, with general allowances for adjustments to punctuation and word dividers.

Composing literature in palindromes is an example of constrained writing. The word "palindrome" was coined from the Greek roots palin (πάλιν; "again") and dromos (δρóμος; "way, direction") by the English writer Ben Jonson in the 17th century. The Greek phrase to describe the phenomenon is karkinikê epigrafê (καρκινικὴ επιγραφή; "crab inscription"), or simply karkinoi (καρκίνοι; "crabs"), alluding to the movement of crabs, such as an inscription that may be read backwards.

Read more about Palindrome:  History, Long Palindromes, Biological Structures, Computation Theory, Semordnilap, Non-English Palindromes