Tribology is an interdisciplinary science and technology that has wide-ranging relationships with many disciplines and technologies. Therefore, the building of a tribology database needs the cooperation of many groups. To assure better communication, it is very important to standardize terminology in building the tribology database. The data dictionary provides a useful tool for the standardization of terminology; it can give the terminology and data in the database three unified characteristics: name, form, and definition. All messages or metadata which relate to the system of the database should be kept in the data dictionary, and it should be possible to query all the messages in the data dictionary for addition, deletion, or modification as necessary. Any change of terms and data name etc. during the building, operation, and maintenance of the database will be reflected, transmitted, and unified in time by the data dictionary.