Merriam-Webster Collegiate Dictionary - shimmer

 I. verb  (~ed; ~ing)  Etymology: Middle English schimeren, from Old English scimerian; akin to Old English scinan to shine — more at shine  Date: before 12th century  intransitive verb  1. to shine with a soft tremulous or fitful light ; glimmer  2. to reflect a wavering sometimes distorted visual image  transitive verb to cause to ~  Synonyms: see flash  II. noun  Date: 1821  1. a light that ~s ; subdued sparkle or sheen ; glimmer  2. a wavering sometimes distorted visual image usually resulting from heat-induced changes in atmospheric refraction  • ~y adjective