The Collaborative International Dictionary of English v.0.48:

dayspring \day"spring`\ (d[=a]"spr[i^]ng`), n.
   The beginning of the day, or first appearance of light; the
   dawn; hence, the beginning. --Milton.
   [1913 Webster]

         The tender mercy of our God; whereby the dayspring from
         on high hath visited us.                 --Luke i. 78.
   [1913 Webster]

WordNet (r) 3.0 (2006):

dayspring
    n 1: 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, sunup, cockcrow]
         [ant: sundown, sunset]

Easton's 1897 Bible Dictionary:

Dayspring
   (Job 38:12; Luke 1:78), the dawn of the morning; daybreak.
   (Comp. Isa. 60:1, 2; Mal. 4:2; Rev. 22:16.)