One embodiment provides a method, including: receiving a query from a user; identifying that a desired definition of the at least one term is unknown, by determining that the at least one term does not map to a term having a known definition; receiving the definition of the at least one term from the user; adding the definition to a domain grammar comprising (i) domain-specific terminology and (ii) definitions corresponding to the terms within the domain grammar, wherein the adding comprises (a) extracting expressions from the requested definition and (b) adding, for the at least one term, the expressions into a structured format within the domain grammar; combining (iii) the requested definition and (iv) terms from the parsed query having previously known definitions into a complete query; and providing a response to the query by executing the complete query on a knowledge store.