Skip to main content
Dictionary
Store
Blog
World
Help
Advertise
Chat
System Status
Information Collection Notice
Trademark Concerns
reCAPTCHA Privacy
Terms of Service
reCAPTCHA Terms
Privacy Policy
Accessibility
Report a Bug
Data Request
Contact Us
Security
DMCA
© 1999–2026 Urban Dictionary ®
Mugs
Tees
Hoodies
Pro Customization
Create unique products with your own words and definitions
Preview
Personalize Your Design
Your Word
Your Definition
The first nuclear bomb, "Little Boy," which was dropped on Hiroshima during World War II, used uranium-235. Little Boy utilized a gun-type design where two sub-critical masses of uranium-235 were brought together rapidly to achieve a supercritical mass, initiating a nuclear chain reaction and resulting in a devastating explosion.
Text fits
Save
Cancel