Sometimes, sovereign
Any 9-letter word that starts with s? Start with statetroom
registrar
startling
That's startling.
sixteenth, squeamish
Kangaroos, keepsakes.
ludicrous litigious
strengths
Sasquatch, sixteenth, squeamish
A 13-letter word that starts with "s" and ends with "s" is "schoolteachers."
Here's a quick one smooching
Stop is a word of warning. It starts with the letter s. Shut up also can be a word of warning.