I’ve randomly noticed an odd dip in the use of patriarchy, patriarchal, and feminism as words in Google’s nGram Viewer starting around a peak in 1999-2000 and continuing until 2008-2009. I’m curious what may have caused this? One could also add the word “gender” which shows a similar dip, but it tends to drown out the signal of the other three, so I’ve removed it here.