comparing words

its a web-based program about anachronisms in historical fiction. the user chooses century and then decade for what he is writing for. then either he upload his file to the text box, or he types in the textbox the historical fiction. the program must compare the words in the textbox (having in mind the choosen century/decade) with the words in the database. the words in the database have an associated date; i.e from when date and after can be used. then every error found in the script, must be shown:underline, highlight, or in a table; in order to be change. If there are any synonyms that can be used in the choosen date, then it should appear as a choice. for example: user chooses: 15th century, 1460-1469 decade he types in the textbox: the girl went for a walk listening to her ipod. the program must identify the word "ipod" as error. in this case there is not a word equivalent to "ipod" in order to have a choice to change it.