The word palindrome is from the Greek palíndromos, meaning running back again (palín = AGAIN + drom-, drameîn = RUN). A palindrome is a word or phrase which reads the same in both directions. Some simple examples are:
RACECAR DEED LEVEL PIP ROTOR CIVIC POP MADAM EYE NUN RADAR TOOT
The longest single English word in common usage which is a palindrome is REDIVIDER, although the contrived chemical term DETARTRATED is two letters longer.
A heteronym that is spelt the same as another word both forward and backwards.