boulevard: [18] Boulevard is a frenchified version of German bollwerk ‘fortification’ (the corresponding anglicized version is bulwark). The meaning of the French word, apparently quite divergent from that of bulwark, comes originally from the practice of constructing walkways along the top of demolished ramparts. => bulwark
boulevard (n.)
1769, from French boulevard (15c.), originally "top surface of a military rampart," from a garbled attempt to adopt Middle Dutch bolwerc "wall of a fortification" (see bulwark) into French, which at that time lacked a -w- in its alphabet. The notion is of a promenade laid out atop demolished city walls, a way which would be much wider than urban streets. Originally in English with conscious echoes of Paris; since 1929, in U.S., used of multi-lane limited-access urban highways. Early French attempts to digest the Dutch word also include boloart, boulever, boloirque, bollvercq.