| Abbreviation | Definition |
|---|---|
| NTBSA | North Thornton Baseball and Softball Association |
| NTBSA | North Thornton Baseball Softball Association |
| NWBI | Northwest Baseball Institute |
| NWL | Northwoods baseball League |
| NYB | Noblesville Youth Baseball |
| NYRB | Nevada Youth Recreational Baseball |
| OACB | Oriole Advocates Challenger Baseball |
| OAPBA | Orlando American Professional Baseball Association (Orlando, FL) |
| OB | Organized Baseball |
| OBA | Opponent Batting Average |
| OBA | Orinda Baseball Association |
| OBC | Obligatory Baseball Comment |
| OBR | Official Baseball Rules |
| OHSAS | Ohio Hot Stove Baseball |
| OMLB | Official Major League Baseball |
| OMLB | Online Major League Baseball |
| OPBL | Ocean Pacific Baseball League |
| OPS | OBP (On Base Percentage) Plus SLG (Slugging Percentage) |
| ORBA | Oxford Recreational Baseball Association |
| OSBA | Ontario Senior Baseball Association |