This is the 4119th most frequent Turkish word.
kapısı
"Kapısı" means "its/her/his/the door" in English.
In this sentence, 'kapısı' indicates possession using the possessive suffix '-ı', referring to 'the door of the house'.
Evin kapısı açık bırakılmış.
The house's door was left open.
Here, 'kapısı' again shows possession, specifying 'the gate belonging to the garden'.
Bahçenin kapısı sabah açıldı.
The gate of the garden was opened in the morning.
In this example, 'kapısı' is modified with '-n-' to denote an object being acted upon and is in the accusative case to identify 'the door of the library' as the object of the action.