nose in a book, have one's

Be constantly reading, as in Walter is known for having his nose in a book. This expression graphically depicts immersing oneself in reading. [Mid-1900s]

The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.