bascule
(also bascule bridge)
/ˈbaskjuːl/
noun
1 A type of bridge with a section which can be raised and lowered using counterweights.
1.1 A movable section of road forming part of a bascule bridge.
Origin
Late 19th century: ‘see-saw’, from battre ‘to bump’ + cul ‘buttocks’.
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Bob pedaled along on his bicycle until he reached the bascule bridge. He crossed the slippery span, in its down position, on foot, pushing the bike, Then he continued rolling on home.