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

Organic Mode

    A term used by COCOMO to describe a project
   that is developed in a familiar, stable environment.

   The product is similar to previously developed products.  Most
   people connected with the project have extensive experience in
   working with related systems and have a thorough understanding
   of the project.  The project contains a minimum of innovative
   data processing architectures or algorithms.  The product
   requires little innovation and is relatively small, rarely
   greater than 50,000 DSIs.

   (1996-05-29)