seal of the confession
• (n.) A seal.
Si·gil'lum noun ; plural Sigilla . [ Latin ] (Rom. & Old Eng. Law) A seal. 
sigillum A seal. Seen on the seals of states, cities, universities, etc.
(pl. sigilla) An impressed, sclerotized spot, often reddish-brown. Often present on the dorsal surface of the abdomen and marking points of internal muscle attachments.