Ess

Ess is the name of the letter S in the Latin alphabet. It is pronounced /ˈɛs/ in English and is the 19th letter of the English alphabet. The word ess is used both to refer to the letter as a symbol and to the /s/ sound it commonly represents.

Historically, the letter S traces its lineage to the Semitic letter shin or sin and was adopted into the Greek alphabet as sigma before entering the Latin alphabet. Its form and usage have varied across ancient and modern scripts, but the modern S is widely recognized across many languages.

In English orthography, the letter S serves several functions beyond representing the /s/ sound. It marks plurals and possessives with the suffix -s or -es and appears in many words where the /s/ sound occurs. The suffix -ess has historically formed feminine agent nouns, as in actress or goddess; contemporary usage increasingly favors gender-neutral terms in some contexts.

Beyond language, S is a common symbol in science and mathematics. It denotes entropy in thermodynamics and information theory, arc length in geometry, and various state or scale quantities in physics and computer science. As a variable, S appears in formulas across disciplines, reflecting its versatility as a symbolic letter.