Adoniram is a peculiar character in Freemasonry. He is another figure not mentioned in Craft Masonry, but makes an appearance in the Cryptic degrees in the American York Rite and the Lodge of Perfection of the Ancient & Accepted Scottish Rite. In Freemasonry, Adoniram is Hiram's successor after the Tragedy of the Third Degree. His appearance comes to us suddenly, abruptly, and he is elevated to a place of great importance with little explanation as to why.
Focusing primarily on the York Rite of Freemasonry, Adoniram appears in the Royal Master degree of the Cryptic Rite. In the first section of the Royal Master there is a conversation held between Adoniram and Hiram Abiff where a lecture that is one of the most beautiful and impacting seen in Freemasonry. If I had to describe in one word the lesson of Adoniram I would choose "Duty"; duty to improve ourselves and the world around us with the finite amount of time we have in this world. There are many theories as to who Adoniram was and there are some who theorize that he is one and the same as Hiram Abiff as they say Adoniram is two names compounded: "Adon" meaning Lord and Hiram, but many reject this as Adoniram is named as the overseer of the workmen in Lebanon and never named to be a worker of brass as Hiram Abiff was; both men appear to be two separate individuals. Out of all the various theories there emerged in Europe a clandestine group known as Adoniramite Freemasonry or sometimes referred to as the Adoptive Rite, but as it was not sustained by the Scriptural history or Masonic tradition it soon ceased to exist.
Adoniram can also be found in the Bible where he is named in charge of those working for King Solomon. In 1 Kings 4:6 he is said to be "over the tribute" and in 1 Kings 5:14 was "over the levy" that was sent to Lebanon. Some believe that Adoniram is the same as Adoram named in 2 Samuel 20:24 who was named to be "over the tribute" under King David, but there is debate as Adoniram is listed to have worked for King Rehoboam (who succeeded Solomon) 47-years after Adoram is mentioned in the 2nd Book of Samuel. 1 Kings also mentions a man named Hadoram that was stoned to death by the people while in discharge of his duties as treasurer or tax-collector. Some still say they were the same person as it is unlikely that even two persons with the similar name would bear the same office and that it is not impossible for someone to have served in officer for 47-years and could have, with this length of time, served in various positions for David, Solomon, and Rehoboam.
Although not tied with the legend of Craft Masonry, Adoniram plays an important figure as the one that succeeded Hiram Abiff as Chief Architect of the Temple. This role isn't necessarily backed up by Biblical references, but the Scriptures do point him out as a prominent figure in the King's Court and relied upon for important aspects of the building of King Solomon's Temple. As with many ancient Biblical figures there is debate as to whether Adoniram is in fact Hiram Abiff, but many do not believe as it is not strongly supported. It is still unclear as to how he gained prominence, but it is believed Adoniram came about as a result of various orders that emerged in France. Remember to be diligent to our duty to God, Country, Family/Friends, and to the Craft.