v. t. [ L. assibilatus, p. p. of assibilare to hiss out; ad + sibilare to hiss. ] To make sibilant; to change to a sibilant. J. Peile. [ 1913 Webster ]
v. t. & i. To pronounce with a hissing sound, like that of the letter s; to mark with a character indicating such pronunciation. [ 1913 Webster ]