The main objective of this paper is to propose a new machining feature definition model focused on 5D-machining features. The machining features describing a Prisronal part, which includes both prismatic and rotational features, are introduced. The unique model is not only taking into account geometric entities, manufacturing aspects but also including machining processes and knowledge-based rules for intelligent process planning system of five-axis lathe. Geometric entities are specified by defining feature parameters corresponding to the shape of feature. Manufacturing aspects include properties of blank part, settings up and technological data like tolerances and surface finishing. Machining processes and knowledge-based rules attached with each feature are used as constraints to guide the system for automatically selecting suitable machining operations. Various examples of 3D & 5D-machining feature attached with knowledge-based for machining those features by five-axis lathe are shown. Finally, the pilot implementation of machining features for operation selection is demonstrated using the expert system shell named Visual Rule Studio/spl trade/ from Rule Machines corporation.