A palindrome is a word, phrase, sentence, or number that reads the same way backwards as it does forward. Palindromes have an ancient history, going back thousands of years. There are numerous examples of palindromes, including the ones below:
"A car, a man, a maraca."
"Able was I ere I saw Elba"
"Madam, in Eden I'm Adam"
"Ah, Satan sees Natasha"
"Dogma: I am God"
"Are we not drawn onward, we few, drawn onward to new era?"
There are many more examples that can be provided, but these should suffice for purposes of defining and demonstrating what is meant by the word "palindrome." Serious aficionados of palindromes -- and, apparently, they do exist -- devise different methods of employing them, for example, in grids or tables known as "palindromic squares."
I have a bit of a silly reference for you, but I feel it may be helpful in remembering what a palindrome is, as it is very catchy. This song will never leave you without a palindrome example again! http://www.youtube.com/watch?v=JUQDzj6R3p4