The Collaborative International Dictionary of English v.0.48:

Ox \Ox\ ([o^]ks), n.; pl. Oxen. [AS. oxa; akin to D. os. G.
   ochs, ochse, OHG. ohso, Icel. oxi, Sw. & Dan. oxe, Goth.
   a['u]hsa, Skr. ukshan ox, bull; cf. Skr. uksh to sprinkle.
   [root]214. Cf. Humid, Aurochs.] (Zool.)
   The male of bovine quadrupeds, especially the domestic animal
   when castrated and grown to its full size, or nearly so. The
   word is also applied, as a general name, to any species of
   bovine animals, male and female.
   [1913 Webster]

         All sheep and oxen, yea, and the beasts of the field.
                                                  --Ps. viii. 7.
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   Note: The castrated male is called a steer until it attains
         its full growth, and then, an ox; but if castrated
         somewhat late in life, it is called a stag. The male,
         not castrated, is called a bull. These distinctions are
         well established in regard to domestic animals of this
         genus. When wild animals of this kind are spoken of, ox
         is often applied both to the male and the female. The
         name ox is never applied to the individual cow, or
         female, of the domestic kind. Oxen may comprehend both
         the male and the female.
         [1913 Webster]

   Grunting ox (Zool.), the yak.

   Indian ox (Zool.), the zebu.

   Javan ox (Zool.), the banteng.

   Musk ox. (Zool.) See under Musk.

   Ox bile. See Ox gall, below.

   Ox gall, the fresh gall of the domestic ox; -- used in the
      arts and in medicine.

   Ox pith, ox marrow. [Obs.] --Marston.

   Ox ray (Zool.), a very large ray (Dicerobatis Giornae) of
      Southern Europe. It has a hornlike organ projecting
      forward from each pectoral fin. It sometimes becomes
      twenty feet long and twenty-eight feet broad, and weighs
      over a ton. Called also sea devil.

   To have the black ox tread on one's foot, to be
      unfortunate; to know what sorrow is (because black oxen
      were sacrificed to Pluto). --Leigh Hunt.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Musk \Musk\ (m[u^]sk), n. [F. musc, L. muscus, Per. musk, fr.
   Skr. mushka testicle, orig., a little mouse. See Mouse, and
   cd. Abelmosk, Muscadel, Muscovy duck, Nutmeg.]
   1. A substance of a reddish brown color, and when fresh of
      the consistency of honey, obtained from a bag being behind
      the navel of the male musk deer. It has a slightly bitter
      taste, but is specially remarkable for its powerful and
      enduring odor. It is used in medicine as a stimulant
      antispasmodic. The term is also applied to secretions of
      various other animals, having a similar odor.
      [1913 Webster]

   2. (Zool.) The musk deer. See Musk deer (below).
      [1913 Webster]

   3. The perfume emitted by musk, or any perfume somewhat
      similar.
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   4. (Bot.)
      (a) The musk plant (Mimulus moschatus).
      (b) A plant of the genus Erodium (Erodium moschatum);
          -- called also musky heron's-bill.
      (c) A plant of the genus Muscari; grape hyacinth.
          [1913 Webster]

   Musk beaver (Zool.), muskrat (1).

   Musk beetle (Zool.), a European longicorn beetle (Aromia
      moschata), having an agreeable odor resembling that of
      attar of roses.

   Musk cat. See Bondar.

   Musk cattle (Zool.), musk oxen. See Musk ox (below).

   Musk deer (Zool.), a small hornless deer (Moschus
      moschiferus), which inhabits the elevated parts of
      Central Asia. The upper canine teeth of the male are
      developed into sharp tusks, curved downward. The male has
      scent bags on the belly, from which the musk of commerce
      is derived. The deer is yellow or red-brown above, whitish
      below. The pygmy musk deer are chevrotains, as the kanchil
      and napu.

   Musk duck. (Zool.)
      (a) The Muscovy duck.
      (b) An Australian duck (Biziura lobata).

   Musk lorikeet (Zool.), the Pacific lorikeet (Glossopsitta
      australis) of Australia.

   Musk mallow (Bot.), a name of two malvaceous plants:
      (a) A species of mallow (Malva moschata), the foliage of
          which has a faint musky smell.
      (b) An Asiatic shrub. See Abelmosk.

   Musk orchis (Bot.), a European plant of the Orchis family
      (Herminium Minorchis); -- so called from its peculiar
      scent.

   Musk ox (Zool.), an Arctic hollow-horned ruminant (Ovibos
      moschatus), now existing only in America, but found
      fossil in Europe and Asia. It is covered with a thick coat
      of fine yellowish wool, and with long dark hair, which is
      abundant and shaggy on the neck and shoulders. The
      full-grown male weighs over four hundred pounds.

   Musk parakeet. (Zool.) Same as Musk lorikeet (above).

   Musk pear (Bot.), a fragrant kind of pear much resembling
      the Seckel pear.

   Musk plant (Bot.), the Mimulus moschatus, a plant found
      in Western North America, often cultivated, and having a
      strong musky odor.

   Musk root (Bot.), the name of several roots with a strong
      odor, as that of the nard (Nardostachys Jatamansi) and
      of a species of Angelica.

   Musk rose (Bot.), a species of rose (Rosa moschata),
      having peculiarly fragrant white blossoms.

   Musk seed (Bot.), the seed of a plant of the Mallow family
      (Hibiscus moschatus), used in perfumery and in
      flavoring. See Abelmosk.

   Musk sheep (Zool.), the musk ox.

   Musk shrew (Zool.), a shrew (Sorex murinus), found in
      India. It has a powerful odor of musk. Called also
      sondeli, and mondjourou.

   Musk thistle (Bot.), a species of thistle (Carduus
      nutans), having fine large flowers, and leaves smelling
      strongly of musk.

   Musk tortoise, Musk turtle (Zool.), a small American
      fresh-water tortoise (Armochelys odorata syn. Ozotheca
      odorata), which has a distinct odor of musk; -- called
      also stinkpot.
      [1913 Webster]

WordNet (r) 3.0 (2006):

musk ox
    n 1: large shaggy-coated bovid mammal of Canada and Greenland;
         intermediate in size and anatomy between an ox and a sheep
         [syn: musk ox, musk sheep, Ovibos moschatus]