IPR
- IMes
- Independent Public Radio
- Indicação de Proveniência Regulamentada
- Indie Press Revolution
- Institute for Plasma Research
- Institute for Policy Research and Catholic Studies
- Institute for Public Relations
- Institute of Pacific Relations
- Intellectual property rights
- Inter partes review
- Interlochen Public Radio
- Interproximal reduction
- Iowa Public Radio
- Mikael Ter-Mikaelian Institute for Physical Research
- Northwestern University Institute for Policy Research
- Prague Institute of Planning and Development
- Purity (quantum mechanics)
- Reclaimed water
- WBST