jolt (v.) Look up jolt at Dictionary.com
1590s, perhaps from Middle English jollen, chollen "to knock, to batter" (early 15c.), or an alteration of obsolete jot (v.) "to jostle" (1520s). Perhaps related to earlier jolt head "a big, stupid head" (1530s). Figurative sense of "to startle, surprise" is from 1872. Related: Jolted; jolting.
jolt (n.) Look up jolt at Dictionary.com
1590s, "a knock," from jolt (v.). Meaning "jarring shock" is from 1630s.