 |
| English | Thesaurus |
| B.O.L. | beginning of life |
| E.O.L. | end of live (of a pacemaker) |
| I/O | Input (voltage earth), Output |
| O.CD. | Ordo Carmelitarum Discalceatorum (Discalced, or Barefoot, Carmelites) |
| O&CO | operations and checkout |
| O.F.M.Cap. | Ordo Minorum Cappucinorum (Capuchins) |
| O&M center | operation and maintenance center |
| O-POS | oxygen-doped polysilicon |
| Program Controlled I/O | PC-I/O |
| SFAE-CD-CO-O | Office symbol for PMCD operations branch |