1. [n]  a weak and tremulous light; "the shimmer of colors on iridescent feathers"; "the play of light on the water"
2. [v]  give off a shimmering reflection, as of silk
3. [v]  shine with a weak or fitful light; "Beech leaves shimmered in the moonlight"

SHIMMER is a 7 letter word that starts with S.

1. \Shim"mer\, v. i. [imp. & p. p. {Shimmered}; p. pr. &
   vb. n. {Shimmering}.] [OE. schimeren, AS. scimerian; akin to
   sc[=i]mian, sc[=i]man, to glitter, D. schemeren, G.
   schimmern, Dan. skimre, Sw. skimra, AS. sc[=i]ma a light,
   brightness, Icel. sk[=i]ma, Goth. skeima a torch, a lantern,
   and E. shine. [root]157. See {Shine}, v. i.]
   To shine with a tremulous or intermittent light; to shine
   faintly; to gleam; to glisten; to glimmer.
   
         The shimmering glimpses of a stream.     --Tennyson.
   
   

2. \Shim"mer\, n.
   A faint, tremulous light; a gleaming; a glimmer.
   
         TWo silver lamps, fed with perfumed oil, diffused . . .
         a trembling twilight-seeming shimmer through the quiet
         apartment.                               --Sir W.
                                                  Scott.