We found one dictionary that defines the word keep something under his hat:

General (1 matching dictionary)

1. keep something under his hat: Merriam-Webster

▸ Words similar to keep something under his hat ▸ Usage examples for keep something under his hat ▸ Idioms related to keep something under his hat ▸ Wikipedia articles (New!) ▸ Words that often appear near keep something under his hat ▸ Rhymes of keep something under his hat ▸ Invented words related to keep something under his hat