| Abbreviation | Definition |
|---|---|
| NYHA | Needham Youth Hockey Association |
| NYHA | Novi Youth Hockey Association |
| NZU | New Zealand Underwater hockey league |
| ODHA | Ottawa and District Hockey Association |
| ODHA | Ottawa District Hockey Association |
| OHA | Ontario Hockey Association |
| OHF | Ontario Hockey Federation |
| OHH | Over the Hill Hockey |
| OHL | Ontario Hockey League |
| OHL | Ontario Hockey Liars |
| OHMB | Original Hockey Mom Brownies |
| OJHL | Ontario Junior Hockey League |
| OMGHA | Osseo Maple Grove Hockey Association (Osseo, MN) |
| OMH | Oshawa Minor Hockey |
| OMHA | Okotoks Minor Hockey Association |
| OMHA | Ontario Minor Hockey Association |
| OMHA | Oromocto Minor Hockey Association |
| OMHA | Oshawa Minor Hockey Association |
| OPHL | Ontario Professional Hockey League |
| OTHC | Oberhausener Tennis und Hockey Club |