A family of Microsoft word processing software products for creating web, email, and print documents.
But note that master documents are buggy in Word. As an alternative, you can use INCLUDETEXT fields as discussed at http://www.word.mvps.org/FAQs/TblsFldsFms/includetextfields.htm.
Note that the article hasn't been updated for recent versions of Word. To display the Insert File dialog box in Word 2007-2013, click the Insert tab, then click the arrow on the Insert button and finally choose Text from File (observe that the command is misleading).
I can't find an ... arrow on the Insert button ...