The Collaborative International Dictionary of English v.0.48:

Adonis \A*do"nis\ ([.a]*d[=o]"n[i^]s), n. [L., gr. Gr.
   'A`dwnis.]
   1. (Gr. Myth.) A youth beloved by Venus for his beauty. He
      was killed in the chase by a wild boar.
      [1913 Webster]

   2. A pre["e]minently beautiful young man; a dandy.
      [1913 Webster]

   3. (Bot.) A genus of plants of the family Ranunculace[ae],
      containing the pheasant's eye (Adonis autumnalis); --
      named from Adonis, whose blood was fabled to have stained
      the flower.
      [1913 Webster]

WordNet (r) 3.0 (2006):

adonis
    n 1: any handsome young man
    2: annual or perennial herbs [syn: Adonis, genus Adonis]
    3: (Greek mythology) a handsome youth loved by both Aphrodite
       and Persephone; "when Adonis died Zeus decreed that he should
       spend winters in the underworld with Persephone and spend
       summers with Aphrodite"

V.E.R.A. -- Virtual Entity of Relevant Acronyms (February 2016):

ADONIS
       ADvanced On-Screen Information System, "AdonIS"