| Abbreviation | Definition |
|---|---|
| BITU | Bustamante Industrial Trade Union |
| BITU | Bustamate industrial trade union |
| BIU | Bermuda Industrial Union |
| BKMU | Bharatiya Khet Mazdoor Union |
| BKU | Bharat Kisan Union |
| BKU | Bharatiya Kisan Union |
| BKU | Bharti Kisan Union |
| BKU | Bhartiya Kisan Union |
| BLET | Brotherhood of Locomotive Engineers and Trainmen |
| BLEU | Belgium Luxembourg Economic Union |
| BLUFF | Bahrain Labour Union Free Federation |
| BMLU | Black Male Leaders Union |
| BMU | Balkan Mountaineering Union |
| BMU | Bell Memorial Union |
| BMU | Blue Mountain Union |
| BMWU | Botswana Mining Workers Union |
| BMWU | Botswana Mining Workers' Union |
| BNTU | Belize National Teachers Union |
| BNTU | Belize National Teachers' Union |
| BOU | British Ornithologists Union |