Comprehensive resource for understanding and mastering English idioms
The idiom "lost in thought" means to be preoccupied or occupied with a particular idea or task, often to the point of being unaware of one's surroundings or what is happening around them. It can also mean being absent-minded or daydreaming.
The idiom "lost in thought" has been used since at least the 16th century in English. One of the earliest known uses of this phrase can be found in the book "A Dialogue Conteinyng the Nomber in Effect All the Prouerbes in the Englishe Tongue" by John Heywood, published in 1546. The idiom was likely used to describe someone who was so absorbed in their thoughts that they had lost touch with reality. Over time, the idiom has evolved to include a wider range of meanings and usages. Today, it is commonly used to describe someone who is daydreaming or absent-minded, as well as those who are deeply engaged in a particular task or idea.