Correct spelling, explanation: worsen is an English verb, which has its origin in the Old Saxon form werran, which used to mean to entangle and referred to a situation that got worse. The form worsen entered English together with a comparative adjective form worse in Middle English. Today, worsen is a commonly used verb.

Definition of worsen:
1. verb – to become worse,
If the fights between the countries continue, the economic situation in the world may worsen.

Expressions with worsen:
A few popular expressions with worsen are: worsen the situation, considerably worsen, and dramatically worsen.
The growing use of cars around the world may worsen the situation of global warming.
Her condition will considerably worsen if she doesn’t undergo a new experimental, medical treatment.
The economic recession will dramatically worsen if the government doesn’t do anything about the problem.

Incorrect spelling, explanation: worsen has a simple spelling and pronunciation, but still it causes a few problems. A number of English speakers confuse the word worsen with the superlative adjective form from this word family, which is worst. As a result, worsen is often misspelled as worsten. It is incorrect and the only proper spelling is worsen.