- \ \  The original meaning of broach was ‘pierce’, and it came from a noun meaning ‘spike’. The word’s ultimate source was the Latin adjective brocchus ‘pointed, projecting’, which in Vulgar Latin came to be used as a noun, *broca ‘spike’. This passed into Old French as broche, meaning ‘long needle’ and also ‘spit for roasting’. English first borrowed the word in the 13th century, as brooch, and then took it over again in the 14th century in the above quoted French meanings. The nominal senses have now either died out or are restricted to technical contexts, but the verb, from the Vulgar Latin derivative *broccare, remains. From ‘pierce’, its meaning became specifically ‘tap a barrel’, which in the 16th century was applied metaphorically to ‘introduce a subject’.\ \ In French, the noun broche has produced a diminutive brochette ‘skewer’, borrowed into English in the 18th century; while a derivative of the verb brocher ‘stitch’ has been brochure, literally ‘a few pages stitched together’, also acquired by English in the 18th century. A further relative is broccoli , plural of Italian broccolo ‘cabbage sprout’, a diminutive of brocco ‘shoot’, from Vulgar Latin *brocca.\ \ Cf.⇒ BROCCOLI, BROCHURE, BROOCH
Word origins - 2ed. J. Ayto. 2005.