In French, the word ‘cahier’ is masculine. This means that when you use articles or adjectives with ‘cahier,’ they should be in their masculine forms. For example, you would say ‘un cahier’ (a notebook) and ‘le cahier’ (the notebook).
Understanding the gender of nouns is important in French because it affects the form of other words in a sentence. For ‘cahier,’ since it is masculine, any adjectives describing it must also be masculine. For instance, ‘un cahier noir’ (a black notebook) uses the masculine form of the adjective ‘noir.’