| Subject | English | Thesaurus |
| abbr. | fail open | fail opened |
| abbr. | fail open valve | fail open |
| abbr. | fail to open | fail open |
| IT, abbr. | Multicast extensions to Open Shortest Path First | MOSPF (routing, IP, OSPF, RFC 1584) |
| abbr., comp., net. | Multicast Open Shortest Path First | MOSPF |
| law, abbr. | Open Court Reading | OCR |
| abbr. | Open Reading Frames in DNA sequences | ORF |
| IT, abbr. | Open Shortest Path First | OSPF (protocol / routing, Internet, IGP, RFC 1583) |
| telecom., abbr. | Open Shortest Path First | OSPF (IETF) |
| abbr., file.ext. | Open Shortest Path First | OSPF |
| telecom. | open shortest path first | OSPF (ssn) |
| IT, abbr. | Open Shortest-Path First Internal Gateway Protocol | OSPFIGP (Internet) |
| abbr., inet. | Open Shortest-Path First Internal Gateway Protocol | OSPFIGP |
| IT, abbr. | Open Transport | OT (Apple) |
| comp., net., abbr. | Open Transport Network | OTN |
| IT, abbr. | Open Transport/Point-to-Point Protocol | OTPPP (Apple, OT, PPP) |
| IT, abbr. | Open Transport/Point-to-Point Protocol | OT/PPP (Apple, OT, PPP) |
| abbr., proj.manag. | Open Work List | OWL (ixtra) |
| IT, abbr. | X/open Transport Interface | XTI (X/Open, X-Windows) |
| abbr., comp., net. | X/Open Transport Interface | XTI |