| Subject | English | Catalan |
| math. | non-null hypothesis | hipòtesi alternativa |
| comp., MS | null character | caràcter nul (" A character code with a null value; literally, a character meaning "nothing." Although it is real in the sense of being recognizable, occupying space internally in the computer, and being sent or received as a character, a NUL character displays nothing, takes no space on the screen or on paper, and causes no specific action when sent to a printer. In ASCII, NUL is represented by the character code 0. ") |
| math. | null hypothesis | hipòtesi nul·la |
| math. | null recurrent state | estat transient (en cadenes de Markov) |
| math. | null recurrent state | estat nul-recurrent |