From WordNet (r) 3.0 (2006):
aurora
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]
2: an atmospheric phenomenon consisting of bands of light caused
by charged solar particles following the earth's magnetic
lines of force
3: (Roman mythology) goddess of the dawn; counterpart of Greek
Eos