What is the correct spelling for the phonetic alphabet term associated with "S"?

The correct spelling for the phonetic alphabet term associated with the letter "S" is "Sierra." In the International Radiotelephony Spelling Alphabet, which is often used in aviation and marine communication to ensure clarity, "Sierra" is specifically designated to represent the letter "S" to avoid misunderstanding over radio transmissions.

Each term in this phonetic alphabet is selected for its pronounceability and distinctiveness over radio. "Sierra" is derived from Spanish and relates to mountainous regions, which provides an easily recognizable term even in challenging communication conditions. The other choices correspond to different letters: "Romeo" is for "R," "Oscar" for "O," and "November" for "N." Each of these terms serves a specific role in helping operators communicate clearly over potentially noisy channels, but only "Sierra" is tied to "S."