A set of interrelated or interacting activities that acts on inputs to produce outputs
Inputs to a process are generally outputs of other processes.
In some processes, some inputs become outputs without any transformation, e.g. a blueprint used in a manufacturing process or a catalyst in a chemical process.
Processess in an organization are generally planned and carries out under controlled conditions to add value.
A process where the confirmity of the resulting output cannot be readily or economically validated is frequently refered to as a "special process". 
 IAEA, Safety Glossary 2007 Edition
 ISO DIS9000:2014, 3.6.1