tessera (n.)youdaoicibaDictYouDict[tessera 词源字典]
plural tesserae, "small, square piece of stone," 1650s, from Latin tessera "a die, cube, square tablet with writing on it" used as a token or ticket, from Ionic Greek tessera, neuter of tesseres (Attic tessares) "four" (see four).[tessera etymology, tessera origin, 英语词源]