The word Sis is misspelled against Siss, a noun meaning "A hissing noise."
-->
Siss has double 'ss' in the end mispronounced as 's'
Remember double 'SS' appears in the end of this word which should not be misspelled with single 'S'
Wrong Spelling:  si-s 
Correct Spelling:  si-ss 
Find more wrongly spelled words of Siss to spell it well.