1. A system comprising: a terminology analyzer configured to: receive a terminology comprising concept-code pairs, each of the concept-code pairs comprising a concept and a code assigned to the concept by the terminology, map the concept-code pairs to at least two different levels of a hierarchical ontology, and associate some of the concepts across different levels of the hierarchical ontology; and an application programming interface (API) comprising at least one function that is configured to: receive a request to access the hierarchical ontology, wherein the request identifies an individual concept, identify the individual concept within an individual level of the hierarchical ontology, and obtain a related concept that pertains to the individual concept, the related concept being obtained from the individual level of the hierarchical ontology or another level of the hierarchical ontology; and at least one processor configured to execute one or more of the terminology analyzer or the at least one function.