Doyen

doyen [doy-ENN]
n. the senior member in age or rank of a group, class, profession, etc.

[Derives from Old French doien, from Late Latin decānus ("chief of ten").]

Doyen has the same etymology as the common English word dean ("the head of a faculty, school, or administrative division in a university or college"). Its direct origins are from Roman Catholicism -- remember that England was a Catholic country until Henry VIII wanted a divorce from Catherine of Aragon in 1533. In Latin, a decānus was "the head of a group of 10 monks in a monastery." That usage, however, was borrowed from the Roman army, where a decānus originally was "a commander of 10 soldiers" and later was extended to civil administrators in the late Roman Empire in charge of at least 9 others. The Latin decānus came from Greek dekanos, which itself is from deka ("ten").

On National Public Radio for years I had heard their plant and gardening expert, Ketzel Levine, referred to as The Doyen of Dirt. At least that's what Scott Simon, the host of Weekend Edition Saturyday, called Ms. Levine. What I didn't ever give thought to when Ketzel was on the radio was, what's a doyen?

A variation of doyen is doyency ("seniority"). In his biography of Theodore Roosevelt called Theodore Rex, Edmund Morris employed that term:

Jusserand and Von Sternburg, both still in Europe, were unable to attend the President's annual Diplomatic Reception on 8 January. ... "Germany" was slashed off the top in pencil: so much for the former doyency of Theodor von Holleben.