O
| Abbreviation | Meaning | Tamil Meaning | Category |
|---|---|---|---|
| O | Engineering Order | - | Organizations |
| O | Opponent | - | ISO Country Codes |
| O | Over | - | ISO Country Codes |
| O | Oberst - Observer - Obstacle - Octal - Officer - Official - Oh - Operational - Operator - Oprah (magazine) - Outstanding -Oxygen | - | Astronomy |