We don't have synonyms for s wave yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are swave, u wave and a wave.
(n) :
Alternative form of S-wave. [(geology, seismology) A transverse, shear wave, such as that produced by an earthquake. Movement is transverse to the direction of propagation and is a body wave.]
(n) :
Alternative form of S-wave. [(geology, seismology) A transverse, shear wave, such as that produced by an earthquake. Movement is transverse to the direction of propagation and is a body wave.]