Definify.com

Webster 1828 Edition

Adj.

Not sifted; not separated by a sieve.

Not critically examined; untried.

Unsight unseen, a vulgar phrase, denoting unseeing unseen, or unseen repeated; as, to buy a thing unsight unseen, that is, without seeing it.

unsifted ‎(not comparable)

Not having been sifted.
If you bake with unsifted flour you don't know how much you are using because it might be packed down or very fluffy.