ostiary
The mouth of a river; an estuary.
archaic
the river of Nilus hath seven ostiaries, that is, by seven channels disburdened itself into the sea
One who keeps the door, especially the door of a church; a porter.
They had other inferiour degrees of the Clergy, vvhich becauſe they are meerly ſubſervient, and not conſiderable in Church-government, I ſhall onely touch upon them. […] Laſtly, Oſtiaries; vvhich uſed to ring the bells, and open and ſhut the Church-doores.
Where it comes from
Borrowed from Latin ostiārius, from ostium (“door, entrance”). See usher, which may be a doublet.
Adapted from the Wiktionary entry ostiary (CC BY-SA 4.0).