| English thesaurus | |||
| |||
| OBS | |||
|
Observation Balloon : 47 phrases in 15 subjects |
| Aeronautics | 1 |
| Artillery | 2 |
| Astronomy | 1 |
| Aviation | 1 |
| Ecology | 2 |
| General | 4 |
| Geophysics | 1 |
| Historical | 1 |
| Makarov | 1 |
| Meteorology | 8 |
| Military | 16 |
| Nautical | 1 |
| Navigation | 2 |
| Physics | 3 |
| Technology | 3 |