What does Antique mean?

In most cases it is a a denim finish achieved by means of sanding and washing, thereby yielding an aged look.

Heddels explains Antique

Since ring spun yarn is never without irregularities, it sometimes gives the denim a special, almost vintage look.  It can also have a light appearance and is hence known to look antique-like.  Thus, the more uneven the yarn, the more antique it is.

However, it is extremely rare for raw denim to (initially) have an antique look as it is raw in nature and completely unwashed.

Additional Resources

The antique effect: