The Collaborative International Dictionary of English v.0.48:

Sphinx \Sphinx\, n. [L., from Gr. sfi`gx, usually derived from
   sfi`ggein to bind tight or together, as if the Throttler.]
   1.
      (a) In Egyptian art, an image of granite or porphyry,
          having a human head, or the head of a ram or of a
          hawk, upon the wingless body of a lion.
          [1913 Webster]

                The awful ruins of the days of old . . .
                Or jasper tomb, or mutilated sphinx. --Shelley.
          [1913 Webster]
      (b) On Greek art and mythology, a she-monster, usually
          represented as having the winged body of a lion, and
          the face and breast of a young woman.

   Note: The most famous Grecian sphinx, that of Thebes in
         B[oe]otia, is said to have proposed a riddle to the
         Thebans, and killed those who were unable to guess it.
         The enigma was solved by [OE]dipus, whereupon the
         sphinx slew herself. "Subtle as sphinx." --Shak.
         [1913 Webster]

   2. Hence: A person of enigmatical character and purposes,
      especially in politics and diplomacy.
      [1913 Webster]

   3. (Zool.) Any one of numerous species of large moths of the
      family Sphingidae; -- called also hawk moth. See also
      tomato worm.
      [1913 Webster]

   Note: The larva is a stout naked caterpillar which, when at
         rest, often assumes a position suggesting the Egyptian
         sphinx, whence the name.
         [1913 Webster]

   4. (Zool.) The Guinea, or sphinx, baboon (Cynocephalus
      sphinx).
      [1913 Webster]

   Sphinx baboon (Zool.), a large West African baboon
      (Cynocephalus sphinx), often kept in menageries.

   Sphinx moth. (Zool.) Same as Sphinx, 3.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Hawk \Hawk\ (h[add]k), n. [OE. hauk (prob. fr. Icel.), havek,
   AS. hafoc, heafoc; akin to D. havik, OHG. habuh, G. habicht,
   Icel. haukr, Sw. h["o]k, Dan. h["o]g, prob. from the root of
   E. heave.] (Zool.)
   One of numerous species and genera of rapacious birds of the
   family Falconid[ae]. They differ from the true falcons in
   lacking the prominent tooth and notch of the bill, and in
   having shorter and less pointed wings. Many are of large size
   and grade into the eagles. Some, as the goshawk, were
   formerly trained like falcons. In a more general sense the
   word is not infrequently applied, also, to true falcons, as
   the sparrow hawk, pigeon hawk, duck hawk, and prairie hawk.
   [1913 Webster]

   Note: Among the common American species are the red-tailed
         hawk (Buteo borealis); the red-shouldered (Buteo
         lineatus); the broad-winged (Buteo Pennsylvanicus);
         the rough-legged (Archibuteo lagopus); the
         sharp-shinned (Accipiter fuscus). See Fishhawk,
         Goshawk, Marsh hawk, under Marsh, Night hawk,
         under Night.
         [1913 Webster]

   Bee hawk (Zool.), the honey buzzard.

   Eagle hawk. See under Eagle.

   Hawk eagle (Zool.), an Asiatic bird of the genus
      Spiz[ae]tus, or Limn[ae]tus, intermediate between the
      hawks and eagles. There are several species.

   Hawk fly (Zool.), a voracious fly of the family
      Asilid[ae]. See Hornet fly, under Hornet.

   Hawk moth. (Zool.) See Hawk moth, in the Vocabulary.

   Hawk owl. (Zool.)
   (a) A northern owl (Surnia ulula) of Europe and America. It
       flies by day, and in some respects resembles the hawks.
   (b) An owl of India (Ninox scutellatus).

   Hawk's bill (Horology), the pawl for the rack, in the
      striking mechanism of a clock.
      [1913 Webster]

The Collaborative International Dictionary of English v.0.48:

Hawk moth \Hawk" moth`\ (m[o^]th`; 115). (Zool.)
   Any moth of the family Sphingid[ae], of which there are
   numerous genera and species. They are large, handsome moths
   with long narrow forewings capable of powerful flight and
   hovering over flowers to feed. They fly mostly at twilight
   and hover about flowers like a humming bird, sucking the
   honey by means of a long, slender proboscis. The larv[ae] are
   large, hairless caterpillars ornamented with green and other
   bright colors, and often with a caudal spine. See Sphinx,
   also Tobacco worm, and Tomato worm.

   Syn: hawk moth, sphingid, sphinx moth, hummingbird moth.
        [1913 Webster + WordNet 1.5] Tobacco Hawk Moth
        (Macrosila Carolina), and its Larva, the Tobacco Worm.
        [1913 Webster]

   Note: The larv[ae] of several species of hawk moths feed on
         grapevines. The elm-tree hawk moth is Ceratomia
         Amyntor.
         [1913 Webster]

WordNet (r) 3.0 (2006):

hawk moth
    n 1: any of various moths with long narrow forewings capable of
         powerful flight and hovering over flowers to feed [syn:
         hawkmoth, hawk moth, sphingid, sphinx moth,
         hummingbird moth]