A person or animal that runs away or has run away; a person, animal, or organization that escapes captivity or restrictions.
"The runaway horse bolted through the open gate and vanished into the dense woods."
Having run away; escaped; fugitive
"The runaway horse bolted through the gate and vanished into the fog before anyone could catch it."
having escaped from the control of the rider or driver
"The horse bolted down the street, turning into a runaway that scared every pedestrian within sight."