Idi can mean:
- Mount Ida, Crete
- Idi Amin, the Ugandan dictator
- Idi, a language of Papua New Guinea
- Iði, a giant in Norse mythology
- Edd, a town in Eritrea
- Azawakh, a dog breed from the Sahel region in Africa
- Mount Ida (Turkey), a mountain in northwestern Turkey, now called Kazdağı or Kaz Dağları or Karataş Tepesi
- The IATA code for Indiana County-Jimmy Stewart Airport, a business service airport in Indiana, Pennsylvania
- Image Diffusion International, a television production company
- Intelligent Devices, Inc., an ITS Intelligent transportation system product company
IDI stands for:
- Israel Democracy Institute
- In-Depth Interview (Market Research)