The adjective is an extension of the past participle.
Disillusioned Sentence Examples
But the defeat of his plans disillusioned him, and he turned to reform.
Frustrated in all his plans, broken-hearted by the death of his son (by his second wife, Marie Ludwika of Angouleme, Wladislaus had no issue), the king, worn out and disillusioned, died at Merecz on the 20th of May 1648, in his 52nd year.
Bruch died a sadly disillusioned man, one who had simply lived too long.
For me, it was the year I became utterly disillusioned with politics.