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.