A situation in which overlapping pages compete for the same search need and create avoidable performance or targeting problems.
Keyword cannibalization describes avoidable problems caused by pages that overlap in the search need they are trying to serve. It is not simply the observation that two pages mention the same words or appear for the same query. A product page and a useful tutorial can share vocabulary while doing different jobs.
Diagnosis should look at actual purpose, content and performance. Similar pages may leave the site without a clear preferred destination for a task, but a report listing multiple URLs is only a starting point. Check whether the pages serve distinct audiences or needs and whether changing them would remove useful information or access.
Possible responses include clearer differentiation, improving navigation or consolidating genuinely redundant material. None should be automatic. If pages are combined, preserve their useful details and route old URLs appropriately. Deleting a page merely because another page ranks for one of its queries can overlook the other needs it satisfies.
Takeaway: Investigate harmful overlap, not shared terminology alone. Keep distinct useful pages, and consolidate only when the evidence and content purpose justify it.
Example
A flooring company has two old articles answering the same question about preparing a room for installation, with conflicting instructions. It reviews whether one maintained guide would serve customers better. Its separate installation-service page remains distinct because it explains the offer and booking process rather than duplicating the preparation guide.
What to check
Compare the pages side by side and review their query and landing-page evidence. Record the intended role of each before changing URLs. If you consolidate, update internal links and verify the replacement destination instead of treating a redirect as the entire editorial fix.
For more detail, see Ahrefs cannibalization explanation.