Nora: A Vocabulary Discovery Tool for Concept Extraction.

Coverage of terms in domain-specific terminologies and ontologies is often limited in controlled medical vocabularies. Creating and augmenting such terminologies is resource intensive. We developed Nora as an interactive tool to discover terminology from text corpora; the output can then be employed to refine and enhance natural language processing-based concept extraction tasks. Nora provides a visualization of chains of words foraged from word frequency indexes from a text corpus. Domain experts direct and curate chains that contain relevant terms, which are further curated to identify lexical variants. A test of Nora demonstrated an increase of a domain lexicon in homelessness and related psychosocial factors by 38%, yielding an additional 10% extracted concepts.