tes·ser·al \-sərəl\adjective alsotes·su·lar\-syələ(r)\ Etymology:tesseral from tessera + -al; tessular from (assumed) New Latin tessula (diminutive of Latin tessera) + English -ar 1.: of, relating to, or resembling a tessera : tessellar 2.: having or constituting an isometric system : regular < a tesseral crystal >