This word is acceptable for play in the US & UK dictionaries that are being used in the following games:

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n. One of the small squares of stone or glass used in making mosaic patterns.

n. A small square piece of stone, wood, ivory or glass used for making a mosaic.

n. complex-ridged surface feature seen on plateau highlands of Venus and perhaps on Triton

n. A small piece of marble, glass, earthenware, or the like, having a square, or nearly square, face, used by the ancients for mosaic, as for making pavements, for ornamenting walls, and like purposes; also, a similar piece of ivory, bone, wood, etc., used as a ticket of admission to theaters, or as a certificate for successful gladiators, and as a token for various other purposes.

n. In zoology, a small, squarish plate of bone such as those forming the carapace of armadillos and glyptodons.

n. A small piece of hard material, generally square in plan, used in combination with others of similar character for making mosaics. Tesseræ are small in surface, and are thick in proportion, and therein differ from tiles, which are large and flat.

n. A die for playing fames of chance.

n. A small square of bone, wood, or the like used in ancient Rome as a ticket of admission to the theater, etc.

n. Same as tessera hospitalis (which see, below).

n. a small square tile of stone or glass used in making mosaics

"I just noticed your blog has a subtitle "Tessera are the small pieces that make up a mosaic" which first rang a bell and immediately afterwards set off my grammar nazi alarm bell, as I remembered that 'tessera' is a singular and the plural would be 'tesserae'."

tessera nummaria    tessera hospitalis    tessera militaris    tessera theatralis    tessera frumentari   

tesserae   

tesseract    tessellate   

remember    quosuch    side wind    write-in    nightram    typesetting    styphnate    ifthey    sonarman    desegregation