What phonetic term corresponds to the letter 'S'?

The phonetic term that corresponds to the letter 'S' is Sierra. This term is part of the International Radiotelephony Spelling Alphabet, also known as the NATO phonetic alphabet, which was designed to provide clarity and reduce misunderstandings when communicating letters over radio or telephone, especially in noisy environments. Each letter of the alphabet is represented by a specific word; for example, 'A' is represented by Alpha, 'B' by Bravo, and so forth.

Sierra specifically represents the letter 'S', providing a standardized way to indicate this letter clearly, which is especially useful in contexts like military, aviation, and maritime communications. This standardization helps avoid confusion that might arise from similar-sounding letters.