5. A computer program product for creating subject matter synonyms from definitions of terms defined in a subject matter glossary, the computer program product comprising a non-transitory computer readable storage medium having program code embodied therewith, the program code executable by a processor to perform a method comprising: extracting from a subject matter glossary definitions of terms defined in the subject matter glossary, wherein the subject matter glossary comprises a list of terms associated with a particular subject matter, and wherein each of the terms is accompanied in the subject matter glossary by one or more definitions; determining a plurality of confidence scores by applying natural language processing to the definitions extracted from the subject matter glossary, wherein each confidence score represents a likelihood that two terms defined in the subject matter glossary are synonyms, and wherein determining a plurality of confidence scores by applying natural language processing to the definitions extracted from the subject matter glossary includes calculating a total confidence score for two terms defined in the subject matter glossary based on a plurality of the confidence scores determined for those two terms; building a subject matter thesaurus based on the confidence scores, wherein the subject matter thesaurus comprises a list of synonyms associated with that particular subject matter organized in a list of synonym pairs, wherein each of the synonym pairs includes two terms defined in the subject matter glossary that are synonyms, and wherein building a subject matter thesaurus based on the confidence scores includes marking those two terms as synonyms if the total confidence score calculated for those two terms is greater than a first threshold; determining the first threshold using machine learning.
6. The computer program product as recited in claim 5 , wherein the natural language processing includes at least one of passage term matching, lexical matching, and syntactic matching.