Sometimes, retina display support may not be enabled after applying the Office 14.2.4 update. To fix this, follow these steps:
Ensure all Office for Mac applications are completely closed. If a program icon appears open on the Dock, hold the Control key, click the icon, and then choose Quit.
With Finder open, choose Go > Applications.
Find Microsoft Office 2011 in your Applications folder.
While holding the Option key, drag the Microsoft Office 2011 folder to your desktop. You should see a green plus symbol next to your cursor to show that you're copying the folder and not moving it.
Once the copy finishes, right-click (or Control + Click) the original Microsoft Office 2011 folder and choose Move to Trash.
Click and drag the Microsoft Office 2011 folder that is currently on the desktop back into the Applications folder. Once the folder has finished moving back into the Applications folder, launch an Office for Mac 2011 application and see if the application now displays in a HiDPI mode.