This is the 1065th most frequent Spanish word.
necesarios
Necessary.
The word 'necesarios' is used as an adjective to describe 'libros', indicating the requirement of those books to complete something.
Esos libros son necesarios para completar el curso.
Those books are necessary to complete the course.
In this sentence, 'necesarios' modifies 'esfuerzos', showcasing a quality attributed to the efforts that make them indispensable for a purpose.
Los esfuerzos necesarios para lograr el objetivo deben ser entendidos.
The necessary efforts to achieve the goal must be understood.
Here 'necesarios' defines 'pasos', emphasizing the indispensability of these steps for achieving the given objective.