The word registered is an adjective. Registered means (1) (of a boat or vessel) furnished with necessary official documents specifying ownership etc.
Registered is also an adjective that means (1) listed or recorded officially, (2) (of animals) officially recorded with or certified by a recognized breed association; especially in a stud book.
The following articles and web pages elaborate on the word registered.
Evite has more than 15 million registered users, making it the top online destination for invitations. Evite is free, thus saving users money on paper products. Besides cards, Evite offers party planners, customizable designs, drink calculators, themed party plans, recipes, and a wine pairing chart. Other types of cards and gifts can be found on the site.
Registered users of the board discuss a variety of issues, including directories and directory scripts, web hosting, search engine optimization, web design, and others. Registration is free, but required for participation.
The following digital image illustrates the word registered.