Definition from Wiktionary, the free dictionary
- Disturbed, upset.
- I was unsettled by the sudden outburst, and since I didn't know what to do I just stood there, confused.
- Not in a steady condition, uncertain, subject to change.
- Not populated, having no settlers or other inhabitants.
- We need to settle this bill; even if you think the charge is too high we can't just leave it unsettled.
Derived terms 
- simple past tense and past participle of unsettle