1. A method comprising: under control of one or more computer systems configured with specific executable instructions, determining a genre of an electronic book based at least in part on a prior categorization of the electronic book, the prior categorization having previously classified the contents of the electronic book; receiving, on an electronic book reader device displaying the electronic book, a request for a definition of a word found within contents of the electronic book; selecting, based at least in part on the determined genre of the electronic book, a dictionary entry from multiple different dictionary entries each providing a definition of the word; locating the definition of the word from the selected dictionary entry; displaying the definition of the word from the selected dictionary entry on the electronic book reader device at least partly in response to the receiving of the request receiving feedback regarding the determined genre or the selected dictionary entry; and determining a different genre of the electronic book based at least in part on the received feedback.
1. A method comprising: under control of one or more computer systems configured with specific executable instructions, determining a genre of an electronic book based at least in part on a prior categorization of the electronic book, the prior categorization having previously classified the contents of the electronic book; receiving, on an electronic book reader device displaying the electronic book, a request for a definition of a word found within contents of the electronic book; selecting, based at least in part on the determined genre of the electronic book, a dictionary entry from multiple different dictionary entries each providing a definition of the word; locating the definition of the word from the selected dictionary entry; displaying the definition of the word from the selected dictionary entry on the electronic book reader device at least partly in response to the receiving of the request receiving feedback regarding the determined genre or the selected dictionary entry; and determining a different genre of the electronic book based at least in part on the received feedback. 11. A method as recited in claim 1 , wherein the determined genre comprises a genre of a first portion of the electronic book, and further comprising: determining a different genre of a second, different portion of the electronic book; receiving, on the electronic book reader device displaying the electronic book, a request for a definition of a word found within the second portion of the electronic book; selecting, based at least in part on the determined genre of the second portion of the electronic book, a dictionary entry from multiple different dictionary entries each providing a definition of the word found within the second portion; locating the definition of the word found within the second portion from the selected dictionary entry; and displaying the definition of the word found within the second portion from the selected dictionary entry on the electronic book reader device at least partly in response to the receiving of the request.