Watertight(adjective)
Meaning - (of an argument or account) unable to be disputed or questioned.
Hindi meaning:निर्विवाद
Synonyms: Indisputable, Unquestionable, Undeniable
Antonyms: Questionable, Doubtful, Dubious
Example: His argument isn't exactly the most watertight.
Trick to remember: pool ke water ko light rakhne par koi watertight nahi h 
