BROACH (Fr. broche, a pointed instrument, Med. Lat. brocca, cf. the Latin adjective brochus or broccus, projecting, used of teeth), a word, of which the doublet "brooch" (q.v.) has a special meaning, for many forms of pointed instruments, such as a bodkin, a wooden needle used in tapestry-making, a spit for roasting meat, and a tool, also called a "rimer," used with a wrench for enlarging or smoothing holes (see Tool). From the use of a similar instrument to tap casks, comes "to broach" or "tap" a cask. A particular use in architecture is that of "broach-spire," a term employed to designate a particular form of spire, found only in England, which takes its name from the stone roof of the lower portion. The stone spire being octagonal and the tower square on plan, there remained four angles to be covered over. This was done with a stone roof of slight pitch, compared with that of the spire, and it is the intersection of this roof with the octagonal faces of the spire which forms the broach.
Note - this article incorporates content from Encyclopaedia Britannica, Eleventh Edition, (1910-1911)