- ICMB (Institute of Cell and Molecular Biology)
- ICMBC (Imperial College Medics Boat Club)
- ICME (International Council on Materials Education)
- ICMP (Internet Control Message Protocol)
- ICMR (Indian Council of Medical Research)
- ICMS (Integrated Circuit Measurement System)
- ICN (Iowa Communications Network)
- ICNAF (International Commission for the Northwest Atlantic Fisheries (became NAFO in 1978))
- ICNI (Integrated Communication, Navigation, and Identification)
- ICNIA (Integrated Communications, Navigation, and Identification Avionics)
- ICNM (International Center for New Media)
- ICO ("in case of" "in care of")
- ICOA (International CBX Owners Association)
- ICOC (Indianapolis Chamber of Commerce)
- ICOD (Intelligence Cutoff Date)
- ICODE (Icfaian Council for Open and Distance Education, India)
- ICODES (Integrated Computerized Deployment System)
- ICOE (In Case Of Emergency)
- ICOFT (Institutional Conduct of Fire Trainer)
- ICOM (Input, Control, Output, And Means)
- ICON (Isotopes of Carbon, Oxygen, and Nitrogen)
- ICoTA (Intervention and Coiled Tubing Association)
- ICOUR (Irrigation Company for the Upper Regions)
- ICP (Infection control professional)
