Reverse Lexicon: This tool returns a list of Greek or Latin words associated with a particular semantic field. You may go from there to full definitions of those words and to all of their occurrences in the texts. (Note that since the definitions are in English, and since you may browse the texts either in translation or in the original, you don't need to know any Greek or Latin to do this. But it helps.)
Select the Greek or Latin dictionary and then type in an English word to find any definitions that contain it.