¿Mujer vieja o la vieja?

 Each of the 6,500 languages we have, has peculiarities and ways that differ from others. This is called diversity, but I call it "different ways to skin a cat." Different ways to interpret and express thought. 

Reading a book review today, I noticed that the novel is focused on the views of "una mujer vieja." Spanish has the peculiarity of making nouns out of adjectives: "la vieja, el rico, el joven, el alto..." English does not come with this feature: "an old woman, a rich man, the young man, the tall boy..." And we can say "una mujer joven" as oposed to "una mujer vieja." English cannot do that, but it can use adjectives as nouns in the plural: "The old =los viejos. The poor = los pobres."

To say "una mujer vieja se ha casado con un hombre joven" is a grammatical travesty because "una vieja se ha casado con un joven" is more than enough. 

English comes with a nice feature: almost all nouns are also verbs: "paper, to paper." "hand, to hand." "eye, to eye." "pencil, to pencil."