Worshipful Master 
The senior officer of a Masonic Lodge is the Master, normally addressed and referred to as the “Worshipful Master” (in Scotland, and in Lodges under the Scottish Constitution, the “Right Worshipful Master”). The Worshipful Master sits in the East of the lodge room, chairs all of the business of his lodge, and is vested with considerable powers without further reference to the members. He also presides over ritual and ceremonies.
The office of Worshipful Master is the highest honor to which a lodge may appoint any of its members. The office is filled annually by election, often by secret ballot. The requirements as to who is eligible for election as Master vary from jurisdiction to jurisdiction, but the majority of jurisdictions specify that a brother must have served as an installed Warden to qualify. In practice, most lodges will nominate and elect the previous year’s Senior Warden in an uncontested election.
The honorific Worshipful does not suggest that the Master is worshiped, but is used in its original meaning, “worthy of respect”. (Mayors and magistrates in parts of England are also traditionally called “Worshipful” or “Your Worship”, as are certain bodies such as livery companies). French Masons use the word Vénérable as the honorific for their Masters.
At the conclusion of his limited term of office, a Worshipful Master is termed a Past Master. The duties and privileges of Past Masters vary from lodge to lodge and jurisdiction to jurisdiction. For example, in some jurisdictions Past Masters become life members of the Grand Lodge, while in others they are not. In most jurisdictions, a Past Master retains the honorific “Worshipful” (as in “Worshipful Brother Smith”), however there are a few where this honorific is used exclusively for sitting Masters.
The corresponding grand rank is Grand Master. The Grand Master may preside over his Grand Lodge, and also has certain powers and rights in every lodge under his jurisdiction. Grand Masters are usually addressed as “Most Worshipful”, or as in Pennsylvania, “Right Worshipful”.