solid
The Spanish word 'macizo' refers to something being 'solid', 'massive' or 'compact' in English. It is used to describe a physical object that is densely packed or firm, that has strength or substance. The word can also be used metaphorically to depict something as being reliable or sound. The usage depends on the context.
The mountain massif is impressive.
In this context, 'macizo' is used as a noun referring to a compact group of mountains, a 'massif'.
The goldsmith made a solid gold ring.
Here, 'macizo' stands for solid, emphasizing that the ring is not hollow or filled with any other material, but 100% composed of gold.
She has solid arms after so much training.
In this sentence, 'macizos' is used as an adjective to describe something sturdy or robust - her arms - after a lot of physical training.