According to the Merriam-Webster dictionary, the "octo-" prefix refers to the eight points on the popular symbol, but the "thorpe" remains a mystery. One theory claims that it comes from the Old English word for "village," based on the idea that the symbol looks like a village surrounded by eight fields!
Adapted from:
https://www.goodhousekeeping.com/life/g25692093/random-trivia/
