Business Process Modeling Notation - a specific modeling implementation under the “UML” umbrella.
Business Process Modeling Notation is a standard for graphically representing behaviors in a business. It is part of the UML standard. It is very descriptive and can be used to model very complicated processes. Part of this power comes at the cost of simplicity, as there are 116 unique elements to the most-current standard (2.0), which makes BPMN somewhat difficult to interpret, thereby undermining a primary value proposition for the technique.
BPMN is functionally similar to IDEF0 and IDEF3 from the IDEF family (IDEF), or Activity Diagrams from the world of UML/SysML.
Source
BPMN Specification - Business Process Model and Notation