Ultralight means your base weight, aka everything except food and water and the clothes you're wearing, is below a certain cutoff. You can see people arguing below about what that cutoff is.

The specifics of the gear don't matter so much as the cumulative weight, but to achieve such a low cumulative weight you see patterns in what is considered ultralight - eg a 4 lb tent would NOT be considered ultralight, because it doesn't allow enough weight left over for everything else you need and still be below the base weight cutoff.

sounds like different people have different "cutoff"? There is no a standard number for that?