Answer: HERMETIC

AnswerCrossword Clue
HERMETICSealed so as to be airtight
HERMETICAirtight
HERMETICMade airtight by fusion.
HERMETICAirtight.
HERMETICTightly sealed
HERMETICMade airtight
HERMETICCompletely airtight
hermeticairtight (impermeable to air)
hermeticairtight