If you are doing a translation and you were sent several PDFs as reference, you can combine them all - in order to do a term seach easily - as follows:
Go to your Windows Explorer
Go to the folder where you have all your reference PDFs (put them all together in the same folder)
Select all PDFs you want to combine (mouse-click + shift)
will all those PDFs selected, right-click on "Combine in Adobe Acrobat"
it will ask you to name and save the newly created file and you're all set!
NOTE: this will work if you have Adobe Acrobat 7.0 or higher.
Hope it helps!