The idea is that you determine the weights of terms based on their frequency in both the current document and in your overall corpus. This lets you find documents based on terms they use that are less frequent overall, and thus that are likely to indicate what the document is about.
Terminology mining is a technique by means of which "interesting" terms can be found in a document. The interesting terms can then be researched in advance of the translation process, so that the translation itself can be both consistent and quick.
There are lots of links I want to save that are tangentially related to this sort of textual analysis.