| WORD | NAME | DESCRIPTION | |
| OBSTETRICS | Healthcare | 35102050 - Obstetrics and Gynecology Biopharmaceuticals | Full Description |
| OFFICEEQUIP | Technology | 55151030 - Office Equipment Products | Full Description |
| OFFICESUPPLY | Consumer Cyclicals | 20151520 - Office Supplies and Stationery Retail | Full Description |
| OFFPRICERETAIL | Consumer Non-Cyclicals | 50101525 - Off-Price Retailers | Full Description |
| OILGASFIELD | Energy | 25102015 - Oil and Gas Field Support Activities | Full Description |
| OILGASINTEG | Energy | 252010 - Integrated Oil and Gas Exploration and Production Since 2018-02-02, previously FOSSILFUELINT.XX1 | Full Description |
| OILGASINTEGSS | Energy | 2520 - Integrated Oil and Gas Exploration and Production Since 2018-02-02, previously FOSSILFUELINT.XX1 | Full Description |
| OILGASOPER | Energy | 25102020 - Oil and Gas Operations Support Activities | Full Description |
| OILGASSUPPORT | Energy | 251020 - Support Activities for Oil and Gas Operations | Full Description |
| OILGASTRANSPORT | Energy | 25102010 - Oil and Gas Transportation and Infrastructure | Full Description |
| OMN | Country IDs | Oman | |
| ONCOLOGY | Healthcare | 35101015 - Oncology Biopharmaceuticals | Full Description |
| OPHTHALMOLOGY | Healthcare | 35102055 - Ophthalmology Biopharmaceuticals | Full Description |
| Or | Boolean operators | Expr1 Or Expr2: Evaluates to 1 when one, or both Expressions is non zero. | |
| ORE | Non-Energy Materials | 451525 - Metal Ore Mining | Full Description |
| OREBASE | Non-Energy Materials | 45152510 - Base Metal Mining | Full Description |
| OREMULTI | Non-Energy Materials | 45153010 - Multi-Product Mining | Full Description |
| ORENONMETAL | Non-Energy Materials | 45153015 - Nonmetallic Mineral Mining | Full Description |
| OREOTHER | Non-Energy Materials | 45152515 - Other Metal Ore Mining | Full Description |
| ORGANICCHEM | Non-Energy Materials | 45101010 - Organic and Petrochemical Products | Full Description |
| OTC | Universe IDs - Other USA | Over The Counter | |
| OUTSOURCEDBIOMED | Healthcare | 35152015 - Other Outsourced Biomedical Services | Full Description |
| OUTSOURCEDDRUG | Healthcare | 35152020 - Outsourced Drug Services | Full Description |