unsafe
unsanitary
unsatisfactory
unsatisfied
unsavory
unsavoury
unscathed
unscheduled
unscientific
unscramble
unscrew
unscrupulous
unscrupulousness
unseal
unseemly
unseen
unselfish
unselfishness
unsettle
unsettling
unshackle
unshakable
unshakeable
unshaven
unsheathe