This is the 15299th most frequent German word.
unsichtbar
Invisible.
The word 'unsichtbar' is used here as an adjective to describe the ghost in the story, meaning it cannot be seen.
Der Geist in der Geschichte war unsichtbar.
The ghost in the story was invisible.
Here, 'unsichtbar' metaphorically describes the feeling of being unnoticed or overlooked in social settings.
Manchmal fühle ich mich in großen Gruppen unsichtbar.
Sometimes I feel invisible in large groups.
In this case, 'unsichtbar' refers to forces of nature that cannot be directly perceived visually, emphasizing their imperceptible quality.