secondary keywords
Also called: secondary keyword, supporting keyword, supporting keywords, related keywords
Secondary keywords are related search terms a page targets alongside its primary keyword. They share the primary term's intent but use different phrasing (synonyms, variations, subtopics), so one page can rank for many queries instead of just one.
A page that ranks well rarely ranks for only one phrase. Ahrefs found the average #1 result also ranks for close to 1,000 other keywords, so the traffic from supporting terms usually dwarfs the primary keyword’s own volume. Secondary keywords are how you claim that traffic without spinning up a thin page for every variation.
Finding and placing them
Good sources are the “also rank for” terms of the current top 10, autocomplete, related searches, and People Also Ask. Semrush suggests roughly 1-2 primary and 4-10 secondary keywords per page, grouped on one URL rather than split across pages (splitting invites cannibalization).
Placement is not a checklist to stuff. Work the terms into H2 and H3 subheadings, the opening paragraphs, image alt text, and body copy where they read naturally. An FAQ block is a clean home for question-shaped variants.
Google’s own guidance is the guardrail. Write for the words your audience actually uses, vary phrasing so you are not repetitive, and stop short of keyword stuffing, which is a spam-policy violation. Secondary keywords work because they map to real subtopics and synonyms Google already associates with the primary intent, not because the terms hit some target count.
How it affects your traffic
Optimizing for secondary keywords is one of the highest-return on-page moves because it multiplies the queries a single URL can rank for without producing new content. A page built only around its primary term leaves the long tail (plus a lot of AI-search and voice phrasing) on the table. Mapping the right supporting terms into headings, FAQs, and body copy is core to our On-Page SEO work, where the goal is to turn one ranking page into a hub that captures hundreds of related searches.
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