Crossword puzzles will often have abbreviations like SSGT or SST or SSN or SSW, and you might consider onomatopoeic things like sss, but there are no regular English words that start with a double s.
Sunrisesspaciousstudioussensuoussonorousscissorssleeplessstraplessshiftlessshirtlessshinglessightlesssalacious
super
scoopscootshootsheetsheepsheersloopspoonspoolsleeksleepsnoopsteepstoopsteersweepsweetswoop
Words beginning with the letter s that describe people:sarcasticscatterbrainsselfishseriousshysillysinceresloppysmartsneakysnobbishsnottysophisticatedspookysqueamishstingysympathetic
spacioussizablesubstantialsuper-sized
Suez.
seat
Squat is a five-letter synonym for sit.
slingstungstingswingswung
Zoris are Japanese sandals. Most all others would be four letter words with an 's' added, such as zebra(s), zebu(s), zero(s), etc.
Sandal, Shoe, Slipper,
Gauntness, Gauntlets