Google’s getting smart, not only basing its algorithm on existing natural language theories and references but also the feed of billions of searches performed by people around world daily. It learns from you.
For example, Google knows PC and laptop are common types of computer, while when you search ‘computer’ alone it would present results by this arbitrary word, you can command it to give a wider range of results including those by its synonyms such as PC, laptop and so forth.
Just search:
~computer
With the tilde character immediately before the searching term (no space between them), Google will yield results not only by the specific phrase but also those similar in meaning.