sibilation (part of speech: noun)
- A hissing conversation it is true, but not unmodulated or without considerable variety in it; a long sibilation would be followed by distinctly- heard ticking sounds, as of a husky- ticking clock, and after ten or twenty or thirty ticks another hiss, like a long expiring sigh, sometimes with a tremble in it as of a dry leaf swiftly vibrating in the wind. - "Far Away and Long Ago", W. H. Hudson.
- S. S has a hissing sound, as sibilation, sister. - "A Grammar of the English Tongue", Samuel Johnson.
- The oats hung their curved heads of little pendulous bells, and gave out a low murmuring sibilation- its only lament that its day was over, and sun and wind no more for it. - "Alec Forbes of Howglen", George MacDonald.