Airtight

Part of speech: adjective

Definitions

1. Fully sealed with no air allowed to pass through, ensuring no leaks or openings ; something that is so logically sound that it cannot be disputed or disproved
2. Impermeable to air, tightly closed to block any exchange of gases ; a reasoning or argument that is flawless and leaves no room for doubt
3. Containing no gaps or holes for air to enter or escape, forming a perfect seal ; an argument or explanation so strong that it is impossible to challenge

Etymology: "Airtight" is a plain compound: "air" joined to "tight," meaning sealed so that no air can get through. Neither part needed to change its shape to make the combination, so the word reads almost exactly as it sounds. The figurative sense, an argument or explanation so sound that no one can find a way to break it, grows naturally from the literal one. A container with no gaps is one nothing can leak out of or into, and an argument with no gaps is one nothing can get past. The metaphor is a simple transfer from physical sealing to logical sealing, which is why the two senses sit comfortably side by side.

Synonyms: sealed, impermeable, inaccessible, soundproof, secure

Antonyms: leaky, open, exposed, permeable, vulnerable