- DAY stands for Do Anything Yourself
- DAY stands for Detroit Asian Youth Project (Michigan)
- DAY stands for Dial-A-Yield (variable yield nuclear weapon)
- DAY stands for Day Centre for Alzheimer’s in York Region (Ontario, Canada)
- DAY stands for Drugs, Alcohol, and Youth
- DAY stands for Dayton, OH, USA – James M Cox Dayton International (Airport Code)
- DAY stands for Development Aid for Youth
DAY