The thing that I imagine in my head when someone says "dragon" is something that I could touch (just as much as the thing I imagine in my head when someone says "apple" is something that I could touch).

I can't touch the Colossus of Rhodes as it no longer exists, but that doesn't make it tangible, so it need not exist right now. If someone genetically engineers a dragon in the future, does that retroactively make dragons tangible today?