This is the 2102nd most frequent Spanish word.
circular
To move or flow around; to circulate.
In this sentence, 'circular' is used as a verb meaning 'to move or travel' in a general sense, often referring to vehicles driving.
Es peligroso circular sin luces en la carretera durante la noche.
It is dangerous to drive without lights on the highway at night.
Here, 'circular' is used as an adjective to describe the shape of the flashlight, meaning 'circular in form' or 'round'.
La linterna tiene un diseño circular que facilita su manejo.
The flashlight has a circular design that makes it easy to handle.
In this sentence, 'circular' is a noun meaning 'an official communication or notice distributed to a group of people, typically by an organization or authority.'