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Synonyms for Beaver (same or very similar meaning)

WordNet sense 1 (the soft brown fur of the beaver):
beaver fur

WordNet sense 2 (a native or resident of Oregon):

WordNet sense 3 (a man's hat with a tall crown; usually covered with silk or with beaver fur):
stovepipe, topper, dress hat, high hat, opera hat, silk hat, top hat

WordNet sense 4 (a hat made with the fur of a beaver (or similar material)):

WordNet sense 5 (work hard on something):
beaver away

From the ODE community, based on WordNetadd/edit