2. A retrieving apparatus comprising: a plurality of first storing units including a content-information storing unit that stores therein electronic program guide data concerning a broadcasted content and a content-material storing unit that stores therein additional information including a recorded content and at least a part of the electronic program guide data for the recorded content; a second storing unit that stores a word dictionary in which a plurality of registered words, a reading of each of the registered words, a family attribute representing a relation between a formal name and an alias of the formal name among the registered words, and a presence attribute representing from which of the content-information storing unit and the content-material storing unit each of the registered words is extracted are associated; an external communication unit that acquires a web page on a network; and an extracting unit that extracts a word that is in a family relation with a registered word in the word dictionary and a reading of the word from a character string included in the web page; a registering unit that registers, in the word dictionary, the word extracted from the electronic program guide data and the additional information, in association with the presence attribute, and that registers the word and the reading of the word extracted by the extracting unit in the word dictionary in association with a family attribute representing the family relation with the registered word; a speech input unit that receives an input of a speech signal; a speech recognizing unit that recognizes a character string corresponding to the speech signal as a keyword; a retrieval-candidate expanding unit that retrieves a word coinciding with the keyword and a word familiar with the word from the word dictionary as a retrieval candidate word; a retrieval-word selecting unit that receives a selection designation that designates any of words included in the retrieval candidate words as a retrieval word; a retrieval-word expanding unit that sets the retrieval word and a word familiar with the retrieval word as expanded retrieval words, based on the word dictionary; and a retrieving unit that retrieves a content related to any of words included in the expanded retrieval words from one of the content-information storing unit and the content-material storing unit represented by the presence attribute associated with the word.
2. A retrieving apparatus comprising: a plurality of first storing units including a content-information storing unit that stores therein electronic program guide data concerning a broadcasted content and a content-material storing unit that stores therein additional information including a recorded content and at least a part of the electronic program guide data for the recorded content; a second storing unit that stores a word dictionary in which a plurality of registered words, a reading of each of the registered words, a family attribute representing a relation between a formal name and an alias of the formal name among the registered words, and a presence attribute representing from which of the content-information storing unit and the content-material storing unit each of the registered words is extracted are associated; an external communication unit that acquires a web page on a network; and an extracting unit that extracts a word that is in a family relation with a registered word in the word dictionary and a reading of the word from a character string included in the web page; a registering unit that registers, in the word dictionary, the word extracted from the electronic program guide data and the additional information, in association with the presence attribute, and that registers the word and the reading of the word extracted by the extracting unit in the word dictionary in association with a family attribute representing the family relation with the registered word; a speech input unit that receives an input of a speech signal; a speech recognizing unit that recognizes a character string corresponding to the speech signal as a keyword; a retrieval-candidate expanding unit that retrieves a word coinciding with the keyword and a word familiar with the word from the word dictionary as a retrieval candidate word; a retrieval-word selecting unit that receives a selection designation that designates any of words included in the retrieval candidate words as a retrieval word; a retrieval-word expanding unit that sets the retrieval word and a word familiar with the retrieval word as expanded retrieval words, based on the word dictionary; and a retrieving unit that retrieves a content related to any of words included in the expanded retrieval words from one of the content-information storing unit and the content-material storing unit represented by the presence attribute associated with the word. 3. The apparatus according to claim 2 , further comprising: a third storing unit that stores a connection destination table in which a field of an object represented by each of the words and a presence location of the web pages corresponding to the fields are associated with each other, wherein the external communication unit acquires the related information from the presence location of the web pages corresponding to the field of the object represented by the registered word, based on the connection destination table.