In the Middle Ages, an obedientiary or obedienciary (from the Latin obedientiarius, meaning someone in an 'obedient', i.e. subordinate, position) was a lesser official of a monastery appointed by will of the superior.
In some cases the word is used to include all those who held office beneath the abbot, but more frequently the prior and sub-prior -who technically qualify in an abbacy- are excluded from those signified by it.
He had as assistants: (4) The refectorian, who had charge of the frater or refectory and its furniture, including such things as crockery, cloths, dishes, spoons, forks etc.
(7) The infirmarian, besides looking after the sick brethren, was also responsible for the quarterly "blood letting" of the monks, a custom almost universal in medieval monasteries.
It was his duty to sing the conventual mass on all days during the week, to intone the Deus in adjutorium at the beginning of each of the canonical hours, to bless holy water etc.