FrameBuilder, a tool for computational lexicography, makes possible the efficient creation of theoretically sound and internally consistent lexical/semantic definitions to a lexical database by a linguistically inexperienced user. The first section describes FrameBuilder as a frame generation component (lexicon builder) of a natural language processing (NLP) system Subsequent sections detail the linguistic theoretical foundation of FrameBuilder, and describe how this expertise is encoded into a system of reasoning-based heuristics for linguistic semantic analysis.