When it comes to teaching machines how to understand human languages, one of the key ingredients is synonyms. Yet what is easy for humans to understand is difficult for machines to grasp.
Search engines are making progress, and Google feels they've made enough progress to make a significant adjustment to their results. Synonyms are now bolded in some search results, just like the keywords from the search phrase are.
Google says this will only happen when their algorithms determine its "useful and important to bold." It's as vague as it sounds.
On the Official Google blog, they gave the example of the search phrase "pictures developed in coffee." In that instance, the word "photos" would also be bolded in the search results, because photos are an obvious synonym of "pictures."
But conduct a search for "earthquake pictures," "cat pictures," or "family pictures" and you're not going to see "photo" highlighted.
Another example Google provided was "himalayan kitten breeder." In this case, the word "cat" is bolded. However, take away the "himalayan" and the word "cat" is not bolded for the search for just "kitten breeder."
Still, Google has weaved into the algorithm a certain intelligence to know what truly determines a synonym. For example, the term "motion picture" should not and does not have the word "photo" bolded in the results, which is good since the phrase is really about film and movies and not about still photos.
This appears to be a very early stage effort by Google to chase the importance of synonyms in the search results. SEO copywriters would be diligent to consider the possibility of expansion of synonyms should Google like how their new feature plays out among searchers.