atardecer

Mainly an impersonal verb describing dusk falling — atardece ("it's getting dark, evening is falling"), used the same grammatical way as llover or anochecer, with no real subject. As a noun (el atardecer) it simply means "sunset, dusk," and that nominal use is actually more frequent in everyday speech than the verb form.

• Ya está atardeciendo, deberíamos volver. — It's already getting dark, we should head back.
• Nos gusta pasear cuando atardece. — We like to go for a walk at dusk.
• El atardecer sobre el mar fue precioso. — The sunset over the sea was beautiful.

Trying to give atardecer a personal subject (*yo atardezco) — like llover and anochecer, it's essentially only used in the third-person singular, describing the sky or time of day itself, not something a person does.

Often confused with anochecer.