A successful lexicographic semantic description characterizes the concepts that occur in establishing the meaning of a listeme by modelling what the competent native-like speaker of the language knows. Because concepts can only be identified to another human through the medium of a natural language, the metalanguage used in the semantic definition of a natural language expression in the object language will always be equivalent to the natural language expression through which that metalanguage is interpreted. The metalanguage of a semantic theory (...) is a demonstrably rational abstract model developed by applying the analyst’s experience and intuitions to inferences drawn from occurrences of actual speech events. Each sense of a listeme is characterized by a description of the salient properties of its typical denotatum. To most effectively implement this project in conceptual engineering is to capture every possible sense of the listeme using metalanguage that is at the same time precise, comprehensive, and succinct. A review of several proposed lexicon/dictionary entries for the listeme cup reveals lacunae that are rectified in a decision procedure whose output characterizes the relevant sense of the input listeme using natural language and the procedural constructs/commands &, XOR, IF, ELSE, ELIF, GOTO, OUTPUT, TENABLE, NEXT ITEM. The resulting lexicographic semantic description satisfies the specified success condition. Establishing the characteristics of metalanguage is crucial to the proper investigation of conceptual engineering. (shrink)