This is the 11473rd most frequent Portuguese word.
octogonal
Having eight sides or angles; octagonal.
Here, 'octogonal' is used as an adjective describing the shape of the glass ('formato octogonal').
O vidro da janela tinha um formato octogonal, o que o tornava único.
The glass of the window had an octagonal shape, which made it unique.
In this sentence, 'octogonal' is used as an attributive adjective ('forma octogonal'), specifying the geometric property of the sign.
Os sinais de trânsito em forma octogonal são usados para indicar uma parada obrigatória.
Traffic signs in octagonal shape are used to indicate obligatory stops.
Here, 'octogonal' functions as a descriptive term for the type of pattern ('piso octogonal').