S, or s, is the nineteenth letter in the Modern English alphabet and the ISO basic Latin alphabet. Its name in English is ess (pronounced /ˈɛs/), plural esses. Northwest Semitic šîn represented a voiceless postalveolar fricative /ʃ/ (as in ‘ship’). It originated most likely as a pictogram of a tooth (שנא) and represented the phoneme /ʃ/ via the acrophonic principle.