Tadoussac (tădˈŏsăk) [key], village (1991 pop. 832), S Que., Canada, at the confluence of the Saguenay and the St. Lawrence rivers. It is a summer resort in a dairying and lumbering region. The site was visited by Jacques Cartier in 1535. An attempt (1600–1601) to establish a French colony there failed, but Tadoussac later became the site of the oldest Christian mission in Canada and an important French fur-trading post.