adventitious (adjective)

1. In the movie, there was an adventitious encounter between the two main characters that changed the course of their lives.

2. The adventitious appearance of a talking dog in the cartoon added a humorous twist to the storyline.

3. The comedian added an adventitious punchline to his joke and it became even funnier.

4. During World War II, the discovery of an adventitious document provided crucial evidence in solving the mystery of a secret mission.