s 1 or S 
(ĕs)
(ĕs)n. pl. s's or S's also ss or Ss
1. The 19th letter of the modern English alphabet.
2. Any of the speech sounds represented by the letter s.
3. The 19th in a series.
4. Something shaped like the letter S.
airplane, Spirit of St. LouisThe single-engine monoplane in which Charles Lindbergh made the first solo nonstop transatlantic flight in 1927 is at the National Air and Space Museum.