There are some talks these days in the blogsphere about Google adding synonyms in their search. Stemming – reducing the words you use to their base form or stem – they have had for a long time (e.g. run, running, runner resulting in the same result-set).
Using synonyms however is a much more complex task and relates to understanding the user’s intentions – including understanding more about the context the user is in. E.g. Port may be substituted by Gate, but also for Wine, and even more complex as we talk various languages into account – Gate in Norwegian also means Street.
So are Google using synonyms as indicated in a few articles referencing an official Google Blog article? Not today from my understanding, but that they are looking into it as a central part of query understanding – for sure. And another Google Blog article explains this much clearer.
Personally, I also believe that their move into the browser market with Chrome positions Google to gather more information about the user’s context. Which is the real problem in current search solutions.