Negativing, Positiving and Sculpting are regular maintenance activities taken on accounts in order to maximise performance.
Negativing refers to blocking either irrelevant search queries on Search, or poor Placements in Display.
Positiving refers to promoting new keywords discovered by mining Search Query reports into their own SKAGs.
Sculpting refers to ensuring the right search queries are being directed to the right SKAGs so that the right ads are being shown. Ultimately, it refers to making sure every Search Query in every account has a clear Line of Sight.