What does 'rock against' mean?

[Jay G.]

Hello,

In the book 'Tuesdays with Morrie', the following appears but I don't know what "He rocked against me" means. Please explain what action was performed. Is it just to move gently to and fro or from side to side? I was trying to find 'rock' in dictionaries but I can't understand exactly. Please, help me.

--- Following ---

Now, five minutes later, Morrie was hugging me, his thinning hair rubbing against my cheek. I had told him I was searching for my keys, that's what had taken me so long in the car, and I squeezed him tighter, as if I could crush my little lie. Although the spring sunshine was warm, he wore a windbreaker and his legs were covered by a blanket. He smelled faintly sour, the way people on medication sometimes do. With his face pressed close to mine, I could hear his labored breathing in my ear.

"My old friend," he whispered, "you've come back at last."

He rocked against me, not letting go, his hands reaching up for my elbows as I bent over him.

I was surprised at such affection after all these years, but then, in the stone walls I had built between my present and my past, I had forgotten how close we once were. I remembered graduation day, the briefcase, his tears at my departure, and I swallowed because I knew, deep down, that I was no longer the good, gift-bearing student he remembered.

[Tdol]

To move the body backwards and forwards without moving the feet is to 'rock'.

[BobK]

When I saw the title of this string, I assumed it would refer to 'Rock Against Racism'. Wrong!

But, in case anyone's interested, this is a slogan in which 'rock' is an abbreviation of either 'rock music' or 'rock culture' - so it behaves like a noun (nothing to do with the verb that Tdol described). (There is also an underlying pun, in which 'rock' is an imperative verb).

b