Latin tessera (plural tesserae), borrowed into English and still live in Italian. It comes from Greek τέσσερα (téssera), the neuter plural of téssares, “four” — the sense being four-cornered.
Its meanings, roughly in order of how you’ll meet them:
- A mosaic tile — the small cube of stone, glass or marble set into a mosaic. This is the main English meaning today.
- A Roman token or tally. A tessera militaris was the wooden tablet carrying the day’s watchword; a tessera frumentaria was a grain-ration token.
- A die — the gaming cube, again from the four-sided/cornered idea.
- In modern Italian, tessera is an everyday word for a membership card, ID card or season pass — tessera sanitaria is the Italian health card.
- In planetary geology, “tesserae” are the heavily deformed, tile-patterned highland terrains on Venus.