tessera
Concise Oxford English Dictionary © 2008 Oxford University Press:
tessera /ˈtɛs(ə)rə/
▶noun (pl. tesserae /-riː/)
- 1 a small block of stone, tile, etc. used in a mosaic.
- 2 (in ancient Greece and Rome) a small tablet of wood or bone used as a token.
– derivatives
tesseral adjective.
tesseral adjective.
– origin C17: via L. from Gk, neut. of tesseres, var. of tessares ‘four’.
'tessera' also found in these Oxford entries:

