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