open question

plural open questions

1. A type of question that cannot be answered with a simple yes or no and requires a longer, more detailed response.

   Thus an open question is one that permits a broad range of responses, while a closed question usually calls for a single-word response such as "yes" or "no" or a number.

   2001, Belainesh Araya, Counseling in an Eritrean Context, page 181

   Synonyms: open-ended question · Antonyms: closed question

2. human sciencesA question whose answer is not fixed by the definition of the terms contained within it.
3. Synonym of open problem.

   Synonyms: open problem