Find the search term you would like to add as a negative keyword.
Click the Add Negative Keywords button.
Select the match type for the negative keyword.
Phrase: Prevents ads appearing if search queries contain the negative keywords in its exact sequence, including queries with words before or after your negative keyword, with allowance for plurals and slight misspellings.
Exact: Prevents ads appearing only if search queries match the negative keyword exactly.
Target: Prevents ads appearing from product pages that match the ASIN exactly.
Use the Negative Keyword field to modify the negative keyword being added if needed.
Phrase: Limit of 4 keywords
Exact: Limit of 10 keywords
Target: Limit of 1 ASIN
Use the selection boxes to select one or more ad groups to add the negative keyword to.
Click Create Negative Keywords button.
Your negative keywords have now been added to the selected ad groups.