In a Sherlock Holmes story, he calls his profession his "metier". This is of French origin, and I haven't
seen it for quite a while.

M'etier \M['e]`tier"\, n. [F.]
Calling; vocation; business; trade.

Not only is it the business of no one to preach the
truth but it is the m['e]tier of many to conceal it.
--A. R.
Colquhoun

From the Latin ministerium 'attendence, service' from minister from the comparative of minus which is already the suppletive comparative of parvus 'small'. The -ter is probably related to the -ster suffix in English. I especially like how French has eviscerated this Latin word.