Google's "Synonyms"

If you do a Google search it will often show results that do not have the word you searched for, but instead include a word that Google has determined to be a synonym.

What is particularly interesting, is that Google doesn't use traditional synonyms.

If you do a search for "activism network", Google shows results with both "activism network" (and note that it highlights "activist network" in the search results), and "activist network". However if you search for "activist network" it only shows results for that. The results for "activism network" are nowhere to be seen. This is because it treats "activism" as a one-way synonym for "activist", but it doesn't treat "activist" that as a one-way synonym for "activism".

The upside of this is that you might be better off optimizing for the "activist" keyword since you will also get traffic from "activism" -- so long other factors (like the level of competition) are equal.