(fandom slang) The ship of characters Steve Rogers (Captain America) and Tony Stark (Iron Man) from the Marvel Cinematic Universe.

As hard as stone.

Containing or made up of stones.

(figuratively) Of a person, lacking warmth and emotion.

(figuratively) Of an action or expression such as a look, showing no warmth of emotion.

(UK and Australia, slang) Short for stony broke: without any money.