It comes from the Latin word "debere" meaning "to owe."
Here are some examples:
* Grateful: Feeling indebted or obliged.
* Spacious: Having ample room, thus giving one the obligation to fill it.
* Hazardous: Risky or dangerous, thus creating an obligation to be cautious.
* Suspicious: Doubtful or distrustful, creating an obligation to investigate.
* Conscious: Aware, giving one the obligation to act responsibly.
However, "ious" can also indicate quality or characteristic. For example:
* Delicious: Having a pleasing taste, highlighting a positive quality.
* Ambitious: Driven by a strong desire for achievement, highlighting a characteristic.
The specific meaning of "ious" will depend on the word it is attached to and the context it is used in.