This is the 700th most frequent Lithuanian word.
dešimtmetį
"Dešimtmetį" means "decade" in English.
Here 'dešimtmetį' refers to a specific period of time, used in accusative case as part of a prepositional phrase.
Per paskutinį dešimtmetį technologijos labai pažengė.
During the last decade, technology has advanced significantly.
In this sentence, 'dešimtmetį' is tied to an event and serves as a descriptor for a celebrated period, used in accusative case for the context.
Lietuva švenčia savo laisvės dešimtmetį.
Lithuania celebrates its decade of freedom.
The word 'dešimtmetį' is used in accusative case to indicate a duration of time over which the action took place.