ADJECTIVE (3)

1. (of animals) officially recorded with or certified by a recognized breed association; especially in a stud book;
- Example: "a registered Percheron"

2. listed or recorded officially;
- Example: "record is made of `registered mail' at each point on its route to assure safe delivery"
- Example: "registered bonds"

3. (of a boat or vessel) furnished with necessary official documents specifying ownership etc;

WordNet (r) 3.0 (2006):

registered
    adj 1: (of animals) officially recorded with or certified by a
           recognized breed association; especially in a stud book;
           "a registered Percheron" [ant: unregistered]
    2: listed or recorded officially; "record is made of `registered
       mail' at each point on its route to assure safe delivery";
       "registered bonds" [ant: unregistered]
    3: (of a boat or vessel) furnished with necessary official
       documents specifying ownership etc

Moby Thesaurus II by Grady Ward, 1.0:

19 Moby Thesaurus words for "registered":
   booked, documented, down, enrolled, entered, filed, indexed,
   inscribed, legal, logged, minuted, of record, official, on file,
   on record, on the books, posted, recorded, written down