1. [n]  large semiaquatic rodent with webbed hind feet and a broad flat tail; construct complex dams and underwater lodges
2. [n]  a hat made of beaver fur or similar material
3. [n]  a movable piece of armor on a medieval helmet used to protect the lower face
4. [n]  a man's hat with a tall crown; usually covered with beaver or silk
5. [n]  a full beard
6. [n]  the soft brown fur of the beaver
7. [v]  work hard on something

Beaver
Examines the beaver's environment, physical characteristics, social life, hunting and mating behavior, and encounters with humans.

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1. \Bea"ver\, n. [OE. bever, AS. beofer, befer; akin to D.
   bever, OHG. bibar, G. biber, Sw. b["a]fver, Dan. b[ae]ver,
   Lith. bebru, Russ. bobr', Gael. beabhar, Corn. befer, L.
   fiber, and Skr. babhrus large ichneumon; also as an adj.,
   brown, the animal being probably named from its color. ?253.
   See {Brown}.]
   1. (Zo["o]l.) An amphibious rodent, of the genus {Castor}.
   Note: It has palmated hind feet, and a broad, flat tail. It
         is remarkable for its ingenuity in constructing its
         valued for its fur, and for the material called castor,
         obtained from two small bags in the groin of the
         animal. The European species is {Castor fiber}, and the
         American is generally considered a variety of this,
         although sometimes called {Castor Canadensis}.
   2. The fur of the beaver.
   3. A hat, formerly made of the fur of the beaver, but now
      usually of silk.
            A brown beaver slouched over his eyes. --Prescott.
   4. Beaver cloth, a heavy felted woolen cloth, used chiefly
      for making overcoats.
   {Beaver rat} (Zo["o]l.), an aquatic ratlike quadruped of
      Tasmania ({Hydromys chrysogaster}).
   {Beaver skin}, the furry skin of the beaver.
   {Bank beaver}. See under 1st {Bank}.
   

2. \Bea"ver\, n. [OE. baviere, bauier, beavoir, bever; fr.
   F. bavi[`e]re, fr. bave slaver, drivel, foam, OF., prattle,
   drivel, perh. orig. an imitative word. Bavi[`e]re, according
   to Cotgrave, is the bib put before a (slavering) child.]
   That piece of armor which protected the lower part of the
   face, whether forming a part of the helmet or fixed to the
   breastplate. It was so constructed (with joints or otherwise)
   that the wearer could raise or lower it to eat and drink.