Prescind derives from the Latin verb praescindere, which means "to cut off in front." Praescindere, in turn, was formed by combining prae- ("before") and scindere ("to cut" or "to split"). So it should come as no surprise that when prescind was first used during the 17th century, it referred to "cutting off" one's attention from a subject. An earlier (now archaic) sense was even clearer about the etymological origins of the word, with the meaning "to cut short, off, or away" or "to sever." Other descendants of scindere include rescind ("to take back or make void") and the rare scissile ("capable of being cut").
Word History
Etymology
Latin praescindere to cut off in front, from prae- + scindere to cut — more at shed entry 1