Keep under one's hat
Meaning
To keep information secret and confidential.
Origin
In an era when hats were a ubiquitous part of daily attire, particularly in the late 19th and early 20th centuries, they served as a symbol of personal space and discretion. The phrase "keep under one's hat" emerged, particularly in American English, evoking the literal act of tucking something away from public view. It conjures the vivid image of a secret so closely held that it's as secure and inaccessible as a private thought literally hidden beneath the brim, known only to the wearer. This transformation of a common accessory into a powerful metaphor for ultimate confidentiality cemented its place in our lexicon.
Examples
- I need you to keep this news under your hat until the official announcement next week.
- She promised to keep the plans for the surprise party under her hat, no matter what.