salient
significant, conspicuous
salutary
healthful; wholesome
sang-froid
calmness, composure or cool self expression
sanguine
cheerful, optimistic
sapient
wise, full of knowledge
saturnine
gloomy, sluggish
savant
a period of extensive learning
scintillate
to sparkle; to twinkle
scurrilous
coarsely abusive, vulgar
sedition
rebellion against the government
sedulous
hard working, diligent
sentient
conscious
shard
a fragment
shibboleth
a slogan, a password
sibilant
a hissing sound