A Passive prot (as opposed to an Active prot) is a monk or ritualist that uses mainly the maintained enchantments (e.g. Life Bond, Life Barrier) of the Protection Prayers line and/or protective passive spirits (e.g. Shelter, Union) of the Communing line. A passive prot has a special role in the party and usually does not cast many spells, even during battle. Her value to the team lies in the enchantments or spirits she maintains on the other party members.
A good example is the bonder.