This is the 12720th most frequent Turkish word.
iradelerinin
"Their wills" (referring to determination or volition).
The word 'iradelerinin' denotes the genitive case of the plural possessive word 'irade' (will), reflecting ownership (of their will).
İnsanların iradelerinin gücüne hayran kaldım.
I was amazed by the power of people's wills.
Here, 'iradelerinin' is used to combine 'irade' with 'talebelerin,' indicating possession by the students, referring to their determination.
Talebelerin iradelerinin sınandığı bir dönemdi.
It was a period when the wills of the students were tested.
In this sentence, 'iradelerinin' refers to the debated concept of animals possessing wills, showing possession.