the meaning of "hang on"

[kjc0123]

What is the meaning of "hang on" in the following sentences?

"I can't believe he's dead." 
"Nor can I. I thought he'd always be here." 
Harry Rex wiped his eyes with the back of a sleeve. "I'm so sorry," he mumbled. "I just can't believe it. I saw him two weeks ago, I guess it was. He was movin' around, sharp as a tack, in pain but not complainin'." 
"They gave him a year, and that was about twelve months ago. I thought he'd hang on, though."

[Ouisch]

They thought he'd "hang on" to life, or keep living, live past the one year estimate the doctor had given him.

[Peter Pedant]

hang on = survive

metaphor. It is as though he is hanging onto a moving vehicle. Or indeed hanging on to life itself

hang on can also mean wait a moment.

As in: Hang on! kjc, there's another meaning to hang on!