Susteinment or Sustainment: How To spell?
The word Susteinment is misspelled against Sustainment, a noun meaning "The act of sustaining; maintenance; support."
Word contains consecutive vowels 'AI' in between alphabets sust & nment is misspelled as 'EI'Wrong Spelling:  sust-ei-nment  Correct Spelling:  sust-ai-nment 
Check more misspelled words of Sustainment to spell it correct.