The Free On-line Dictionary of Computing (30 December 2018):

object relational mapping
object relational modelling

    (ORM) The software development activity
   that defines a correspondence between objects in a program and
   rows in a database table.  Atomic object properties
   correspond to columns in the table, non-atomic data types and
   relations between objects are represented as foreign keys
   referring to other tables.

   An object persistence mechanism is responsible for maintaining
   the correspondence between objects and the database contents at
   run-time.

   (2014-12-03)