13. The non-transitory computer-readable medium of claim 12 , the computer program instructions further comprising instructions for: identifying a term of the plurality of primary and secondary terms occurring in a related content document; extracting content associated with the identified term from the related content document, the extracted content comprising a secondary definition of the identified term; and storing the secondary definition in connection with the identified term.
13. The non-transitory computer-readable medium of claim 12 , the computer program instructions further comprising instructions for: identifying a term of the plurality of primary and secondary terms occurring in a related content document; extracting content associated with the identified term from the related content document, the extracted content comprising a secondary definition of the identified term; and storing the secondary definition in connection with the identified term. 15. The non-transitory computer-readable medium of claim 13 , wherein the educational electronic document is in a first language, wherein the related content document is a dictionary in a second language, and wherein the computer program instructions further comprise instructions for: translating the identified term into the second language; and identifying a definition associated with the translated term in the second language dictionary; wherein extracting the content associated with the identified term comprises extracting the definition associated with the translated term.