Airtight
To be airtight was not to allow any air to escape. Circuit housings on Deep Space 9 were airtight. () 

The term could also describe an alibi's accuracy. In, Odo informed Garak that Kira Nerys had an airtight alibi for his attempted murder. ()

See also
 Airlock
 Hermetic seal

External link

Slang
Science