means To restart a computer or system so it loads fresh from the beginning, often clearing whatever glitch had taken hold.

from A literal child of "boot," which is short for "bootstrap" — from the old impossible image of pulling yourself up by your own bootstraps. Early computers had to load their first instructions seemingly from nothing, lifting themselves into operation by their own metaphorical straps, so starting one up became "booting." Add the prefix "re-" ("again") and you get "reboot": to haul the machine up by its bootstraps a second time. The word later leapt from screens to storytelling, where a "reboot" restarts a tired franchise from scratch.