An enterprise keyword is a word or phrase that is added to items on a SharePoint site. Enterprise keywords are organized into a single, non-hierarchical term set within the Term Store Management Tool called the Keywords set. Because users can typically add any word or phrase to an item as a keyword, enterprise keywords can be used for folksonomy-style tagging. Term store administrators, or other individuals with permission to manage metadata, can opt to move keywords out of the Keywords term set and into a specific managed term set, at which point the keywords will become available within the context of a specific term set. Term Store Administrators can also choose to make the Keywords set closed, so that users cannot submit new keywords and are restricted to the use of existing keywords or managed terms from existing term sets. If you add an Enterprise Keywords column to a list or library, site users will be able to enter keyword values for items stored in the list or library. If the Keywords term set for the site has been configured to be open, users can add any text value to this column.
So from that, as long as you set it to closed, you can pre-populate and give your users an authoritative set to choose from.
Note: You don't have to set it to closed to pre-populate. If you leave the submission policy open, you can still pre-populate, but users will be able to enter their own terms as well.
The Keyword Termset will be under System in your Term Store Management administration.