Stench:
meaning-an unpleasant smell
Sentence-the stench of rotting fish
Stern:
meaning-serious
Sentence- A smile transformed his stern face.
Strive:
meaning-make great efforts to achieve or obtain something.
Sentence- My mother told me to always strive to do my best in school so that I could get into a good college.
Supreme
meaning-a level of high quality.
Sentence-She has an air of supreme confidence about her.
Sustain
meaning-strengthen or support physically or mentally
Sentence-He sustained serious injuries in the accident.