Questions & Answers about Pieczony kurczak jest pyszny.
Because pieczony has to agree with kurczak in gender, number, and case.
- kurczak is masculine singular
- the sentence uses the nominative case, because pieczony kurczak is the subject
- so the adjective/participle must also be masculine singular nominative: pieczony
Compare:
- pieczony kurczak = roasted chicken
- pieczona ryba = roasted fish
- pieczone mięso = roasted meat
Pieczony is a form derived from the verb piec = to bake / to roast. In this sentence, it works like an adjective and means roasted or baked.
So pieczony kurczak literally means roasted chicken.
English learners often think of it as a past participle, and that is a useful way to understand it. In normal Polish usage here, though, it simply behaves like an adjective describing the chicken.