Reading the WordNet license, I do not see a copyleft condition. It is more like the MIT license actually.
This is a hard question to answer in general. There are two issues at hand here.
Firstly, it is possible that the format of a data file is copyrighted (not always the case of course), so that code reading the data file might be considered derivative work of the format. If the license allows so, eg. if the database is free (as in free speech), this can be circumvented by converting the data to a different format for your own need.
Secondly, the selection of data, or the data itself can be copyrighted. When a program reads data, the program is usually not considered a derivative work of said data. If output is generated from the data, it usually inherits the copyright of the data. There may be exceptions, such as if the output is a summary of the data.
In your case, both licenses only require some kind of attribution and are not viral. As long as you comply with the requirements you are fine. The only thing to watch out for is that there may be compatibility issues with GPL.