| Subject | English | Spanish |
| rem.sens. | F number | número F |
| commun., IT | f-number | abertura relativa |
| comp., MS | f-number 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) | apertura de diafragma (número f) |
| chem. | the scum contained a considerable number of sulphate ions but no chloride ions %1F De Vries | el fango contenía grandes cantidades de iones sulfato, pero no de iones cloruro |