- Sealing an area or container so that no air can pass through.
- Making something so that it cannot be criticized or proven false.
From air + tight, from the sense of preventing air from escaping or entering.
- The container was airtight to preserve the food.
- The seal on the lid of the jar was airtight to keep the contents fresh.
- The argument was airtight and left no room for counter argument.
- The evidence was airtight and left no doubt of his guilt.
- The chamber was airtight to maintain the required pressure.