This is the 13590th most frequent German word.
diesjährige
"Diesjährige" means "this year's" in English.
The word 'diesjährige' functions as an adjective describing the specific year of the summer vacation.
Die diesjährige Sommerferien waren herrlich.
This year's summer vacation was delightful.
The word 'diesjährigen' in this sentence is an attributive adjective describing the noun 'Marathon', specifying it as the one occurring in this year.
Wir nahmen am diesjährigen Marathon teil.
We participated in this year's marathon.
Again, the word 'diesjährigen' denotes the competition that took place in the current year and is used attributively with the noun.