1. A glossary management device comprising: either or both of a read circuit that reads a document and an output circuit that outputs the document; a storage circuit that has a storage area for a glossary to which text segments extracted from the document that is read by the read circuit or output by the output circuit are to be added as entry terms; an acquisition circuit that acquires text data of the document; an analysis circuit that performs analysis of the text data acquired by the acquisition circuit to identify a language of the document and parts of speech of text segments in the text data and extracts one or more text segments from the document based on the analysis; a term matching circuit that performs matching for each of the extracted text segments against a public dictionary containing entry terms registered therein; and a registration circuit that adds to the glossary, each extracted text segment that does not match any entry term in the public dictionary.