Senight or Sennight: How To spell?
The word Senight is misspelled against Sennight, a noun meaning "The space of seven nights and days; a week."
Sennight has double "nn" is mispronounced as "n"Remember double 'NN' in between the strings se & ight which should not be misspelled with single 'N'
Wrong Spelling:  se-n-ight  Correct Spelling:  se-nn-ight 
Find more wrongly spelled words of Sennight to spell it well.