What's Vintage?

Out of curiosity, what do you guys consider vintage? Is there a set date or number of years that makes something vintage? I admire and dream of making garments from almost every era from the 20's on up.

The reason I ask is I just made a sundress from a pattern dated 1981. I know you guys are so sweet you would probably like to see it... but was wondering if this was still considered vintage?

Thanks for the input!

~Byrdie