What word describes a chair that is hard to sit on comfortably?

The correct answer, "uncomfortable," accurately describes a chair that is difficult to sit on comfortably. This word is derived from the root "comfort," which refers to a state of physical ease and absence of pain. The prefix "un-" indicates a negation, which means that the chair lacks the quality of comfort. Hence, when someone describes a chair as "uncomfortable," it clearly conveys that the chair does not provide a relaxing or supportive experience for the sitter.

This term effectively communicates the condition of the chair, making it clear that it does not offer the expected comfort. The other choices do not fully express this idea. For instance, "comfortable" would imply that the chair is easy to sit on, while "soft" and "hard" describe the physical characteristics of the chair rather than the experience of sitting on it. Therefore, "uncomfortable" is the most appropriate word in this context, as it directly captures the negative experience associated with sitting on such a chair.