Definition of "Beaver" :

noun: large semiaquatic rodent with webbed hind feet and a broad flat tail; construct complex dams and underwater lodges

noun: a hat made with the fur of a beaver (or similar material)

noun: a movable piece of armor on a medieval helmet used to protect the lower face

noun: a man's hat with a tall crown; usually covered with silk or with beaver fur

noun: a full beard

noun: a native or resident of Oregon

noun: the soft brown fur of the beaver

verb: work hard on something