This is really only relevant to frequent searchers as the average number of terms is still around 2.8... but it's worth remembering because when searching in large full text databases you need to OR all the equivalent terms if you want more recall.
This is my blog on library and information science. I'm into Sci/Tech libraries, special libraries, personal information management, sci/tech scholarly comms.... My name is Christina Pikas and I'm a librarian in a physics, astronomy, math, computer science, and engineering library. I'm also a doctoral student at Maryland. Any opinions expressed here are strictly my own and do not necessarily reflect those of my employer or CLIS. You may reach me via e-mail at cpikas {at} gmail {dot} com.