While it sounds a bit academic and technical it is really quite simple.
If we are talking about any article in French such as 'a' mouse or 'an' apple we are not referring to any particular mouse or any particular apple.
It is just any old mouse or any old apple.
That is why it is an 'indefinite article'.... because it is 'indefinite.'
Once we talk about that exact mouse on the table, or that exact green apple that it is eating, it becomes 'the mouse' and 'the apple'. It refers a particular, definite mouse.
The word 'the' is the definite article.
There are several words for the indefinite article in French.
un - une - des.
The French Indefinite Article - a or an.
French Indefinite articles are used as follows:
• when the noun is not specific - a (any) book, not THE book.
• French Indefinite articles depend on the gender and number of the noun.
Feminine Singular (that is one female object): une
• The indefinite article in French is used even when it is not translated in English
(des translates as some but is omitted in English).
• The exception of the verb être:
• The other exception - When you don’t use the indefinite article in French.
When you are talking about a person’s nationality, religion, or profession, you do not use an article of any kind because those words are considered to be adjectives in French.
There it is, the French indefinite article, a fancy way of saying 'a', 'an', or 'some'.
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