sorprender, to surprise.
sorpresa, f., surprise.
sosiego, m., quiet.
sostener, to hold, hold open.
soy, see ser.
su, his, her, its, their, your, one's.
suavemente, softly, gently.
subir, to go (or come) upstairs, rise.
subsecretario, m., assistant secretary.
suceder, to happen.