In some applications, it may be difficult to represent the exact meaning of an object due to the nature of the environment being modelled. Therefore, the object may only partially match certain properties, and crisp data mining approaches may not be appropriate for this situation. To overcome the situation, a linguistic summary using the fuzzy set theory is developed as the data mining function in the KDD system. Using predefined properties, the proposed summary can answer the question "for each group in the database, which predefined property is shared by largest number of objects?", where the property in the question could fall in the range F1 Ú…Ú Fm rather than a single property, Fi.