More info about synonyms at Google
Steve Baker, an engineer in the search quality group at Google, just did a nice post about synonyms on the Google blog. A lot of people seem to think that Google only does simple-minded matching of the users’ keywords with words that we indexed. The truth is that Google does a lot more sophisticated stuff than most people realize. I’d say that Google does more with “semantics” and both document and query understanding than almost any other search engine.
Read the blog post for more info, but I liked a couple examples that Steve mentioned. “Pictures” and “picture” often mean the same thing, but the query [arm reduction] is very different than [arms reduction]. Also, in the query [dura ace track bb axle njs] the “bb” is probably referring to a bottom bracket while in the query [software update on bb color id] the “bb” probably means blackberry.
However, our measurements show that synonyms affect 70 percent of user searches [note from Matt: of course, it could be a subtle change] across the more than 100 languages Google supports. We took a set of these queries and analyzed how precise the synonyms were, and were happy with the results: For every 50 queries where synonyms significantly improved the search results, we had only one truly bad synonym.
