If something's airtight, it is completely sealed so that no air can get in or out of it. When you make homemade jam with the raspberries you picked, it's important to make sure the lids are airtight so the jam won't spoil. Many kinds of food and medicine you buy in a store are airtight.

What does it mean if something is airtight?

1 : impermeable to air or nearly so an airtight seal. 2a : having no noticeable weakness, flaw, or loophole an airtight argument.

Is there a difference between airtight and watertight?

As adjectives the difference between watertight and airtight

is that watertight is so tightly made that water cannot enter or escape while airtight is being impermeable to air or other gases.