Definition of "strung out"

She believed he was becoming strung out, if he wasn't hooked yet

1971, Donald Goines, Dopefiend, page 20

When I'm out walking, I strut my stuff / Yeah, and I'm so strung out / I'm high as a kite, I just might / Stop to check you out

1983, Gordon Gano (lyrics and music), “Blister in the Sun”, in Violent Femmes, performed by Violent Femmes

When Ted Hollander first agreed to travel to Naples in search of his missing niece, he drew up for his brother-in-law, who was footing the bill, a plan for finding her that involved cruising the places where aimless, strung-out youths tended to congregate.

2010, Jennifer Egan, “Goodbye, My Love”, in A Visit from the Goon Squad

"Permissive" working allows more than one train to be in a block section at one time but trains must be run at low speed in order to stop on sight behind the train in front. Such working is often authorised to allow freight trains to "bunch" together to await a path through a bottleneck instead of being strung out over several block sections, as would be necessary if absolute working were in force.

1962 October, “Talking of Trains: The collisions at Connington”, in Modern Railways, page 232