The active record pattern is an architectural pattern found in software that stores in-memory object data in relational databases. It was named by Martin Fowler in his 2003 book Patterns of Enterprise Application Architecture. (Wikipedia)
ActiveRecord is also the name of a Ruby object-relational mapping library (ORM) which was created as part of the Ruby on Rails framework. It was named after the design pattern, but it has since grown to encompass much more functionality than the original pattern describes.