Source : Webster's Revised Unabridged Dictionary (1913)

Sunup \Sun"up`\, n.
   Sunrise. [Local, U.S.]

         Such a horse as that might get over a good deal of
         ground atwixt sunup and sundown.         --Cooper.

Source : WordNet®

sunup
     n : the first light of day; "we got up before dawn"; "they
         talked until morning" [syn: {dawn}, {dawning}, {morning},
          {aurora}, {first light}, {daybreak}, {break of day}, {break
         of the day}, {dayspring}, {sunrise}, {cockcrow}] [ant: {sunset}]