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El informe tiene una estructura circular.
The report has a circular structure.
Having the shape of a circle; round.
La plaza es circular.
The square is circular.
Moving in a circular path or direction.
El planeta gira en una órbita circular.
The planet orbits in a circular path.
Returning to the starting point; cyclical.
El debate se volvió circular.
The debate became circular.
'Circular' is often used to describe shapes, movements, and cyclical processes.
Do not confuse 'circular' with 'circumferential' (pertaining to the circumference).
From Latin 'circularis', from 'circulus' (circle).
In formal contexts, 'circular' can refer to official documents sent to multiple recipients.