This is the 121st most frequent Italian word.
ieri
"Yesterday."
'Ieri' is used as an adverb of time to specify when the action of going to the cinema occurred.
Ieri sono andato al cinema.
Yesterday, I went to the cinema.
'Ieri' is used as an adjective to describe 'l'evento', indicating the event that occurred the day before today.
L'evento di ieri è stato molto interessante.
Yesterday's event was very interesting.
'Ieri' is used within a phrase that specifies a time relative to a point in the past, 'il giorno prima di ieri' meaning the day before 'yesterday'.