undefined (adjective)

1. The plot of the anime series is undefined, leaving the viewers with many unanswered questions.

2. The horror movie relied on an undefined antagonist, adding to the suspense and fear.

3. My friend told me an undefined joke that left me scratching my head, trying to figure out the punchline.

4. The film's ending was intentionally left undefined, allowing the audience to interpret it in their own way.