A Fremen priestess who supervised all ceremonies involving water and served as the spiritual guide of the sietch. The Sayyadina blessed the daily water distribution, presided over birth and funeral rites, and played a central role in the Water of Life ceremony. A Sayyadina who survived the spice agony could become a Fremen Reverend Mother, gaining access to the ancestral memories of all previous Reverend Mothers. In the absence of a Sayyadina, the most knowledgeable woman in the group could be temporarily consecrated into the office.