This rather rare and specialist word has turned up twice in recent years in newspapers in the UK, in both cases in obituaries of Church of England bishops.
One had the phrase “gremial college”, the other referred to a bishop being “attired in mitre, ceremonial gloves and gremial”. Though they are obviously different senses, it may be surprising to learn that they are closely connected. Both derive from late Latin gremiālis, which in turn comes from the anatomically imprecise gremium, the lap or bosom.
When you are scholastically gremial, you have figuratively laid your head in the welcoming lap or bosom of a university or college: you are not only a member, you’re living there. Older documents would at times refer to non-gremial students who were enrolled but who lived elsewhere. The word was confined to locations in which knowledge of the classical languages was common; though you might also describe servants who lived in as gremial, nobody ever did. Gremial in the clerical context is a silk apron worn during confirmations or when conferring holy orders, to prevent vestments being stained by drips of the chrism oil.
There is a third sense, carrying the idea of a bosom friend, which is actually the oldest. This is now very rare and I can find only one modern use:
“You are very fond of him, I believe?” “Am I? Yes; perhaps I am. I would not call him a gremial friend — I have not known him long enough — but I am very much attached to him. I am sorry that you are not.”
Master and Commander, by Patrick O’Brian, 1970.