bulwark: [15] Bulwark comes from Middle High German bolwerc ‘fortification’, a compound formed from bole ‘plank’ (the same word as English bole ‘tree trunk’) and werc, equivalent to English work. It thus originally meant ‘rampart constructed out of planks or tree trunks’. The word was shared by other Germanic languages, including Swedish bolverk, and French borrowed it as boullewerc, which has since become boulevard. => bole, boulevard, work
