watertight
Concise Oxford English Dictionary © 2008 Oxford University Press:
watertight/ˈwɔːtətʌɪt/
▶adjective
- 1 closely sealed, fastened, or fitted so as to prevent the passage of water.
- 2 (of an argument or account) unable to be disputed or questioned.
'watertight' also found in these Oxford entries:

