(Will appear in the February 2008 issue of Community News
Those of us who are old enough remember when frock was used to refer to a woman's dress. It's a much older word than that, going back at least to the 14th century. In those days, it could mean any item of clothing, for men or women, that was long, loose, and had full sleeves. Over the centuries, frock was applied to various types of clothing, from women's dresses to men's frock coats to various items of sailor's clothing. The clothing worn by a priest was called a frock. If a priest was thrown out of the priesthood, he had to give up his priestly clothes, and he was said to have been defrocked. Because the robes worn by judges are commonly believed to have evolved from the clothing of priests, a judge who is expelled from the bench is also said to be defrocked.
I'm collecting all of these at: http://www.dvorkin.com/davidsdefs.html