aboiteau
/abwɑːˈtəʊ/Canadian
noun
Especially in the Maritime Provinces of Canada: a sluice gate in a dyke, which allows water draining from the land to flow out but does not allow sea water to enter.
Origin
Early 19th century. From Canadian French aboteau, aboiteau, apparently ultimately from Middle French bot elevated bank of a canal, dyke + -eau, suffix, probably via a French regional (western) intermediary.