Word gives you the option to import contacts from your local address book. Mac OS X's address book gives you the ability sync with Google from 10.5.3 onwards. So:
- Open address book
- Go to prefences (command + ,)
- Select the account tabe
- Select your local account
- Check synchronize with Google and follow the instructions
In Word, use the mail merge feature under Tools>Mail Merge and select Apple Address Book as the recipient list.
Note that this solution will add these items to your local address book which might not be desirable. It will also temporarily disable iCloud syncing though it can be re-enabled easily enough. A somewhat more complex option is to select Export from the More menu in GMail Contacts. You can then read the CSV file using Open Data Source in Mail Merge.