Complex sentence: In many Latter Day Saint denominations, an Apostle is also a priesthood office of high authority within the church hierarchy, as a member of the Quorum of the Twelve, although not all apostles have been part of the Quorum.
Split into simpler sentences: In many Latter Day Saint denominations, an Apostle is also a priesthood office of high authority within the church hierarchy. The term usually refers to a member of the Quorum of the Twelve Apostles, although not all apostles have been part of the Quorum.