| Abbreviation | Definition |
|---|---|
| JBN | New Jersey Jackals Baseball Network |
| JBO | Junior Baseball Organization |
| JDBL | Japan Deaf Baseball League |
| JLB | Junior League Baseball |
| JRBC | Juan Romero Baseball Camp |
| JSBA | Jersey Shore Baseball Association |
| JSBL | Jersey Shore Baseball League |
| JVBA | Junior Varsity BAseball |
| JWBL | Japan Women's Baseball League |
| JYB | Jenks Youth Baseball |
| JYBA | Jasper Youth Baseball Association |
| K | Strikeout |
| KABC | Kansas Association of Baseball Coaches |
| KBL | Korean Baseball League |
| KBO | Korea Baseball Organization |
| KBO | Korean Baseball Organization |
| KBSA | Korea Baseball Softball Association |
| KC | Kansas City Royals |
| KMBA | Kamloops Minor Baseball Association |
| KMBA | Kelowna Minor Baseball Association |