noun
1. a former United States executive agency that was responsible for developing atomic bombs during World War II
• Instance Hypernyms: ↑executive agency
• Part Holonyms: ↑executive branch, ↑Executive Office of the President
2. code name for the secret United States project set up in 1942 to develop atomic bombs for use in World War II
• Instance Hypernyms: ↑undertaking, ↑project, ↑task, ↑labor
Useful english dictionary. 2012.