palindrome (n.)youdaoicibaDictYouDict[palindrome 词源字典]
"line that reads the same backward and forward," 1620s, from Greek palindromos "a recurrence," literally "a running back," from palin "again, back" (from PIE *kwle-i-, from root *kwel- (1) "move round," with notion of "revolving;" see cycle (n.)) + dromos "a running" (see dromedary). Related: Palindromic.[palindrome etymology, palindrome origin, 英语词源]