"We have awaited your coming," she said in her sibilant voice.
Two letters, S and O, a sibilant and a vowel, of which no further explanation can be given.
When they spoke Universal, their voices were sibilant, but not nearly so inhuman.
It seemed as if that low, stealthy, sibilant whispering was going on forever.
A sibilant sound from the detective's lips took me to his side.