Explanation:

- Business: This word is spelt correctly. It refers to commercial activity or trade.

- Dreadful: This is also spelt correctly. It describes something that causes fear or is very unpleasant.

- Emergensy: This is the misspelt word. The correct spelling is "Emergency," which refers to a serious, unexpected situation requiring immediate action.

- Inflammable: This word is spelt correctly. It means easily set on fire or capable of burning quickly.

Emergensy is the misspelt word.