A logic diagram, also known as a logic tree or decision tree, is a graphical representation of a logical argument. It is used to illustrate the relationships between different variables and to show how decisions are made based on those variables. The term 'logic diagram' can also refer to a tree-like structure that shows the logical relationships between different components of a system. The crossword solution for the term 'logic diagram' is 'TREE', which is an apt description of this type of diagram.