The Collaborative International Dictionary of English v.0.48:

Annunciation lily \An*nun`ci*a"tion lil"y\ (Bot.)
   The common white lily (Lilium candidum). So called because
   it is usually introduced by painters in pictures of the
   Annunciation.
   [Webster 1913 Suppl.]

The Collaborative International Dictionary of English v.0.48:

Easter lily \Eas"ter lil`y\ (Bot.)
   Any one of various lilies or lilylike flowers which bloom
   about Easter; specif.:
   (a) The common white lily (Lilium candidum), called also
       Annunciation lily.
   (b) The larger white lily (Lilium longiflorum eximium, syn.
       L. Harrisii) called also Bermuda lily.
   (c) The daffodil (Narcissus Pseudo-Narcissus).
   (d) The Atamasco lily.
       [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

Annunciation lily
    n 1: lily of eastern Mediterranean and the Balkans with broad
         funnel-shaped white flowers [syn: Madonna lily, white
         lily, Annunciation lily, Lent lily, Lilium candidum]