An uncorrected proof is a proof version (on paper or in digital form) which is yet to receive final author and publisher approval.
The term may also appear on the covers of advance reading copies; see below.
In his article Collecting Uncorrected Proofs, Ken Lopez concludes “Proof copies, if you follow your nose and are willing to take small risks, can be great investments — because even if the author doesn't “hit” and the monetary values don't go sky-high, you've still got a scarce, unusual, often textually significant 23 mar. 2020
An uncorrected proof is a printed copy of a book that needs to be reviewed for errors and corrections.
They are released prior to official publication, and generally are very plainly bound, and distributed only for final editing or promotion.