This, like our words “sign” and “insignia,” is derived from the Latin sigillum, diminu-tive of signum, meaning a mark, or sign. It is some kind of device affixed to a document in place of a signature or in close connection with a signature for the purpose of showing that the document is regular or official. A document bearing the seal of a Lodge shows that it is officially issued by the Lodge, and not by some irresponsible person or persons. The word is also used of the tool by means of which the device is stamped into wax, or whatever similar material may be used for the purpose.
- Source: 100 Words in Masonry
A stamp on which letters and a device are carved for the purpose of making an impression, and also the wax or paper on which the impression is made. Lord Coke defines a seal to be an impression on wax, sigillum est cera impressa, and wax was originally the legal material of a seal. Many old Masonic Diplomas and Charters are still in existence, where the seal consists of a cireular tin box filled with wax, on which the seal is impressed, the box being attached by a ribbon to the parchment But now the seal is placed generally on a piece of circular paper.
The form of a seal is circular; oval seals were formerly appropriated to ecclesiastical dignitaries and religious houses, and the shape alluded to the old Christian symbol of the Vesica Piscis. No Masonic document is valid unless it has apes pended to it the seal of the Lodge or Grand Lodge. Foreign Grand Lodges never recognize the transactions of subordinate Lodges out of their Jurisdictions, if the standing of the Lodges is not guaranteed by the seal of the Grand Lodge and the signatures of the open officers.
- Source: Mackey's Encyclopedia of Freemasonry