An Etymological Dictionary of the German Language/Annotated/Bruch
Bruch (1.), masculine, ‘breach, rupture, crack,’ from Middle High German bruch, Old High German bruh, masculine; formed by gradation from brechen.
Bruch (2.), masculine, neuter, ‘damp meadow, marsh, bog,’ a Franconian-Saxon word from Middle High German bruoch, Old High German bruoh(hh), neuter masculine, ‘marshy soil, swamp’; compare Low German brôk, Dutch broek, ‘marsh-land,’ Anglo-Saxon brôk, ‘brook, current, river,’ English brook. Similarly Middle High German ouwe combines the meanings of ‘water-stream, watery land, island.’ It is possible that West Teutonic *broka- is allied to brechen, a supposition that has been put forward on account of the Anglo-Saxon meaning ‘torrent’; in that case the Old High German sense ‘swamp’ would be based upon ‘a place where water gushes out.’
Bruch (3.), feminine, neuter, ‘breeches,’ from MidHigh German bruoch, Old High German bruoh(hh), feminine, ‘breeches covering the hip and upper part of the thigh’ (akin to Anglo-Saxon brêc, English breech); compare the corresponding Anglo-Saxon brôc, plural brêc, English breeches, Middle Low German brôk, Dutch broek, Old Icelandic brók, ‘breeches.’ It has been asserted that the common. Teutonic brôk- has been borrowed from the equivalent Gallic-Latin brâca (likewise Romance, compare Italian brache, French braies); but Anglo-Saxon brêc, ‘rump,’ shows that Bruch contains a Teutonic stem; hence the Gallic-Latin word is more likely borrowed from Teutonic; compare Hemd.