airtight
UK: ˈeətaɪt | US: ˈertaɪt
adj. completely sealed to prevent the passage of air or gas
adj. (figuratively) impervious to criticism or logical flaws
The word "airtight" combines "air," from Old English "ær" (meaning the invisible gaseous substance surrounding Earth), and "tight," from Old Norse "þéttr" (meaning dense or impermeable). The compound emerged in the early 19th century, originally describing containers sealed against air leakage. Its figurative use, implying logical or argumentative impermeability, developed later by analogy.
The jar must be airtight to preserve the food's freshness.
Scientists stored the samples in an airtight chamber.
Her alibi was airtight, leaving no room for doubt.
The contract was drafted to be legally airtight.
Ensure the submarine hatch is airtight before diving.