it's named after anatomical structures with the name "rete" (which is just latin for net, but Forgy meant specifically that kind of structure). eg https://en.wikipedia.org/wiki/Rete_mirabile

Source: via Forgy himself, see https://www.youtube.com/watch?v=BUw-67B_qA4#t=4m30s (the video and the blog that goes along with it are really annoying in holding out the explanation until the end)

Thank you!