I was able to replicate the naked woman for that term this morning, so it may still show up for you.
Sarah, a Google User Experience Specialist, explained the issue:
There are a couple of things going on here that could explain why the image made it through Safe Search. Thomas P made some really great points. Just for future knowledge, when issues like this occur help us out and click the Safe Search link next to the Search box and then click to report offensive image. Click the report button on that image and voila!
I took care of reporting this one for you so you don't need to worry about it, but good knowledge any future occurrences.
This may be the first report of nudity in Google's Dictionary.
Forum discussion at Google Web Search Help.