A palindrome is a word, number, phrase, or other sequence of symbols that reads the same backwards as forwards. For example, "racecar" and "madam" are palindromic words. Palindromes can also be phrases, such as "A man, a plan, a canal – Panama". In addition, palindromes can be numbers, such as 1881, which reads the same backward or forward. Palindromes are not limited to the English language, as the Finnish word "saippuakivikauppias" is a palindrome and is the longest single-word palindrome in everyday use.

In genetics, a palindrome is a DNA or RNA sequence that reads the same in both directions. In rheumatology, palindromic rheumatism is a form of joint inflammation in which the joints involved by the arthritis appear to change periodically from one region of the body to another and back again.

The word "palindromic" can also refer to a double-stranded sequence of DNA in which the order of the nucleotides is the same on each side.

Overall, a palindrome is a sequence of letters, numbers, or whole words that reads the same forwards as it does backwards.