Merriam-Webster Collegiate Dictionary - whisper

 I. verb  (~ed; ~ing)  Etymology: Middle English, from Old English hwisperian; akin to Old High German hwispalon to ~, Old Norse hvisla — more at whistle  Date: before 12th century  intransitive verb  1. to speak softly with little or no vibration of the vocal cords especially to avoid being overheard  2. to make a sibilant sound that resembles ~ing  transitive verb  1. to address in a ~  2. to utter or communicate in or as if in a ~  II. noun  Date: 1595  1. something communicated by or as if by ~ing; especially rumor ~s of scandal  2.  a. an act or instance of ~ing; especially speech without vibration of the vocal cords  b. a sibilant sound that resembles ~ed speech  3. hint, trace