This is the 949th most frequent Estonian word.
õhku
"Õhku" in English means "into the air."
In this sentence, 'õhku' functions as a noun in the partitive case, indicating movement into the air.
Lennuk tõusis õhku.
The airplane took off into the air.
Here 'õhku' is used as a noun in the partitive case, referring to the air that needs refreshing.
Õhku tuleb värskendada.
The air needs to be refreshed.
'Õhku' in this context is in the partitive case, representing the gaze directed into the air or atmosphere.