past tense and past participle of seek, from Old English sohte. Sought-after is from 1881 (sought-for in same sense is from c. 1600).
the most sought-after item was the silver candelabrum
the long sought relatives
sou
soubrette
souffle
souffre-douleur
sough
sought
souk
soul
soulful
soulless
soulmate