Negative keywords are terms you add to an ad campaign to prevent your ads from showing when those terms appear in a search query. When a search includes a negative keyword, your ad is suppressed regardless of your bid.
Example: You sell premium stainless steel water bottles. If you add "plastic" as a negative keyword, your ad won't show for "plastic water bottle" — a query that your product cannot satisfy and that would generate clicks without conversions.
Why Negative Keywords Are Essential
Every irrelevant click wastes budget. A campaign without negative keywords will inevitably show ads for searches that have nothing to do with the product. This raises ACOS, lowers CTR (which can reduce ad quality score), and trains the algorithm on bad conversion signals.
Negative keywords are often the fastest lever for improving ACOS without reducing bids.
Match Types for Negative Keywords
| Type | How It Works | Example Negative |
|---|---|---|
| Negative Exact | Blocks only exact search | "free" blocks "free" but not "free delivery" |
| Negative Phrase | Blocks queries containing the phrase | "free" blocks "free water bottle", "get it free" |
On Amazon, there is no negative broad match.
Building a Negative Keyword List
From Search Term Reports: Pull 30–90 days of search term data from Campaign Manager. Sort by spend with zero orders. Terms with $5+ in spend and zero conversions are immediate candidates.
Proactive exclusions (before data): Think about who would NOT buy your product. For a premium kitchen knife set:
- "cheap", "disposable", "toy", "kids", "plastic"
- Competitor brand names (unless you're deliberately conquesting)
- Unrelated category terms that share keywords (e.g., "garden knife" if you only sell kitchen)
Category-level negatives: Add common "deal-seeker" terms as negatives across all campaigns — "free shipping" (already standard on Amazon Prime), "wholesale", "bulk buy" (if you don't sell B2B).
Negative Keywords vs. Campaign Structure
Negative keywords work with campaign structure, not as a replacement. Tightly themed ad groups reduce irrelevant matching at the structure level. Negatives clean up residual mismatches within a well-structured campaign.