lost in thought

lost in thought

not aware of what is happening around you because you are thinking about something else I didn't answer right away because I was lost in thought.
See also: lost, thought

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
References in classic literature ?
When the Emperor's health was drunk, Pierre, lost in thought, did not rise or lift his glass.
He was lost in thought, his book lay unheeded by his side, his silvered iron-grey hair was scattered confusedly upon his forehead as though his hand had been wandering among it while his thoughts were elsewhere, and his face looked worn.
He remained lost in thought for some minutes; and then, with a heavy sigh, snuffed the candle, and, taking up the book which the Jew had left with him, began to read.
That same afternoon, as McMurdo sat smoking, lost in thought beside the stove of his sitting-room, the door swung open and its framework was filled with the huge figure of Boss McGinty.
My companion sat silent for some time, with his chin upon his hand, lost in thought.
She could see him through her tears, blurred to a mere shadow on the white road, and then again becoming more distinct, but always absolutely still and as if lost in thought before a strange phenomenon which demanded the closest possible attention.
I could draw nothing further from him, and he walked, lost in thought, as far as the Baskerville gates.
He appeared to be lost in thought, rolling his eyes about and running a thin nervous hand through his hair.
Then, completely lost in thought, he got up, went up to his mother, kissed her, went back to his place and sat down.