The New Student's Reference Work/S

S (ĕs), the nineteenth letter, is a consonant, often called a sibilant because the true s is a hissing or voiceless consonant. Its proper sound occurs in best, hiss, so. It also has the sounds of z, as in has; sh, as in passion, sensual, version; and zh, as in visual. At the beginning of words s generally has the hissing sound, but at the middle and end its sound is determined by custom. In a few words s is silent, as aisle, débris, island, isle. The nearness of s to th caused th in verbs to become s, as loveth, loves. S sometimes changes to st, as hoist from hoise.