Terminology harmonization involves concepts, concept systems, definitions, and term-concept designations. Harmonization of concepts is the fundamental objective for many applications in terminology work, and the analysis of definition statements is a key to concept identification. Analyzing a definition requires knowledge of the definition type. Examples are given from the 1990 ASTM Compilation of Standard Definitions along with a systematic set of questions that should aid definition writers, standardizes, translators, and others who use definitions in identifying concepts or harmonizing meanings in terminology.