What does the popular TikTok slang 'airtight' really mean?

The slang term 'airtight' has gained popularity online, creating confusion about its meaning. Originally referring to a vacuum-sealed environment, it evolved to describe arguments without flaws. On TikTok, 'airtight' denotes anything flawless, like a look, argument, or skill, akin to saying something is perfect. While not a new phrase, its usage on TikTok reflects the platform's role in evolving language.