lost in thought

lost in thought

Fully and deeply engrossed in a thought or idea, often to such a degree as to be unaware of or insensitive to the outside world. It's no use trying to talk to Helen when she's lost in thought like that; it's as if we don't even exist!
See also: lost, thought
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.

lost in thought

Concentrating on or pondering over something. For example, Gwen didn't hear a word you said; she was lost in thought.
See also: lost, thought
The American Heritage® Dictionary of Idioms by Christine Ammer. Copyright © 2003, 1997 by The Christine Ammer 1992 Trust. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
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