| Intraseasonal Atmospheric Oscillation | Academic & Science |
| International Organization for Standardisation | Academic & Science |
| Isoprenaline | Academic & Science |
| Imamia Student Organization | Academic & Science |
| Indian Student Organization | Academic & Science |
| Isorhapontigenin | Academic & Science |
| Incentive Stock Option | Accounts and Finance |
| Kinston (nc) | Airport Code |
| Iceland Symphony Orchestra | Arts |
| International Symphony Orchestra | Arts |
| derived from the Greek isos, meaning “equal” | Associations & Organizations |
| Interstedelijk Studenten Overleg | Associations & Organizations |
| International Science Olympiad | Associations & Organizations |
| International Organisation for Standardisation | Banking |
| International Society of Organbuilders | Business |
| International Sugar Organization | Business |
| Ishares Standard & Poors/Australian Stock Exchange Small Ordinaries | Business |
| International Standardization Organization | Business |
| Insurance Services Office, Incorporated | Business |
| Industry Standard Operation | Business |
| Intermarket Sweep Order | Business |
| Insurance Service Organization | Business |
| Independent Sales Organization | Business |
| Insurance Services Office | Business |
| Indianapolis Symphony Orchestra | Community |
| International Student Organization | Community |
| Imamia Students Organization | Community |
| Innovative Styling Option | Community |
| I seek only | Community |
| Initial Sign-On | Computing |
| ISO image file format, from the ISO 9660 file system | Computing |
| IEC ISO International Electrotechnical Committee | Computing |
| Information Security Officer | Computing |
| An Iso Image ( File.iso ) Is An Archive File of An Optical Disc. | File Type |
| Iso-9660 Table | File Type |
| International Standards Organisation | General |
| I’m So Odd | General |
| Incentive Stock Options | General |
| Isuzu Sales Operation | General |
| Interior Systems Optimization | General |
| It's Soon Out | General |
| Infringing Software Organization | General |
| International Standard Organization | General |
| International Socialist Organization | Governmental |
| Internal Security Organisation | Governmental |
| International Socialist Organisation | Governmental |
| Internationale Sozialistische Organisatio | Governmental |
| International Standards of Operations | Governmental |
| Intensive Supervision Order | Governmental |
| Istanbul Sanayi Odasi | International |
| International Service Organization | International |
| International Services Office | International |
| International Students Office | International |
| I'm Still Online | Internet |
| Insane Sexual Offer | Internet |
| I'm So Out | Internet |
| Interactive Support Online | Internet |
| It's So Original | Internet |
| Independent Systems Operator | Jobs |
| International Organisation for Standardization | Measurement Unit |
| Immunization Safety Office | Medical |
| ISOpropyl alcohol. | Medical |
| Its So Obvious | Messaging |
| In Search Of | Messaging |
| Insurance Services Organization | Messaging |
| International Standardization Organization Erroneously. Actually The Word Is Greek for "equal" and Iso Is The Name of The Organization. The Expansion Is A Backronym. | Messaging |
| Installation Supply Officer | Military and Defence |
| Integration Staff Officer | Military and Defence |
| Isolation | Military and Defence |
| In Support of .... | Military and Defence |
| Installation Safety Office | Military and Defence |
| International Organization for Standardization | Organization |
| Kinston, North Carolina USA | Regional |
| Imperial Service Order | Society & Culture |
| Imaging Spectrometric Observatory | Space Science |
| Information Systems Office | Space Science |
| Infrared Space Observatory | Space Science |
| Isolated Power | Sports & Games |
| Indexed Stock Option | Stock Exchange |
| refers to the ISO norm for sensitivity of Photographic film or image sensors sensitivity to light | Technology |
| Independent System Operator | Telecommunication |
| International Standards Organization | Telecommunication |
| Kinston Regional Jetport | Transport & Travel |