be sunk in something

be sunk in (something)

To be fully and deeply engrossed in a thought or idea, perhaps because one is feeling melancholy. It's no use trying to talk to Helen when she's sunk in thought like that; it's as if we don't even exist!
See also: sunk

be ˈsunk in something

be in a state of unhappiness or deep thought: She just sat there, sunk in thought.
See also: something, sunk