Microsoft Office is shipped with offline help in compiled form, however starting with Office 2007 it's harder to find these files because they no longer use the .CHM format and instead have opted to use the newer form of compiled help, the Microsoft Help 2 Format (.HXS).
There are a collection of five files that make up the offline help for Microsoft Word:
They can be found on disk where office is installed to, this is normally:
Program Files\Microsoft Office\Office12\1033\
however the exact location may differ as some parts of that path may be different for each machine, for example if you are running 64bit OS then
Program Files will be called
Program Files (x86), likewise the number after office will differ depending on the version of Office you have installed, in this case
Office12 refers to Office 2007.
Also it's useful to note that the help files for the other Microsoft Office products are found in the same location with a similar naming structure as shown above.
When it comes to view these files, more than likely your machine doesn't have a stand alone viewer installed already so you will need to download one first. I recommend downloading the H2Viewer for free. Even more handy is when the H2Viewer is opened it brings up a list of already available HXS files on the machine which you should see the Word help file on that list already.
Once the file is opened you are greeted with the full help content in offline form.