| Subject | English | French |
| rem.sens. | F number | nombre F |
| rem.sens. | F number | ouverture relative minimale |
| med. | f number | ouverture numérique |
| transp., energ.ind. | F2 octane number | indice d'octane moteur |
| astr. | f-number | dénominateur d'ouverture |
| comp., MS | f-number | f : chiffre (In photography, the diameter of the aperture expressed in terms of the focal length of the camera lens. The greater the f-number, the less light reaches the film and the more in focus the objects in the foreground and the background will be. For example, with an f-number = 16 the objects in the far background will be in focus. Whereas, with an f-number = 2 the background will be blurry (while foreground objects are in focus)) |
| tech. | f-number | ouverture relative |
| chem. | the scum contained a considerable number of sulphate ions but no chloride ions %1F De Vries | la boue contenait une grande quantité d'ions de sulfate |
| gen. | the scum contained a considerable number of sulphate ions but no chloride ions %1F De Vries | mais pas d'ions de chlorure |