Noah Webster's New International Dictionary of the English Language

1. (n.) Happy; fortunate; blessed.

2. (n.) Harmless; innocent; inoffensive.

3. (n.) Weak; helpless; frail.

4. (n.) Rustic; plain; simple; humble.

5. (n.) Weak in intellect; destitute of ordinary strength of mind; foolish; witless; simple; as, a silly woman.

6. (n.) Proceeding from want of understanding or common judgment; characterized by weakness or folly; unwise; absurd; stupid; as, silly conduct; a silly question.