difference between virtually and almost

Please read the following

1. This mission is almost impossible to achieve.


2. 
   

   This mission is virtually impossible to achieve.

   
   


3. 
   

   He was almost killed in that accident.

   
   


4. He was virtually killed in that accident.

Cambridge dictionary has given the meaning of virutally as 'almost'

But somehow I think that there has to be some some difference between them.

There are too many times that I come across this 'virtually' word in books and movies. I wonder if it can be used as a synonym for 'almost'? Is there any subtle difference that I should know about ? Are they exactly identical and interchageable in given situation ?

Thanks

Answer

Virtually means "almost (in respect to degree or strength)" or "almost completely".

In your first pair, the difference is very small:

This mission is almost impossible to achieve.

This mission is virtually impossible to achieve.

Here, I think virtually is a stronger choice, so the second sentence simply means the mission is more difficult than the first. Both sentences mean basically the same thing.

Your second pair has a much bigger difference:

He was almost killed in that accident.

He was virtually killed in that accident.

Here, the first sentence can mean either:

• 
  

  He was almost hurt in an accident, but he wasn't hurt at all. (For example, his car almost fell off a cliff, but it didn't fall. He got out safely.)

  
  
  


• 
  

  He was hurt very badly in an accident. He almost died from his injuries.

  
  

On the other hand, the second sentence (with virtually) can mean only the second sense. He was hurt badly and was close to dying.

Perhaps a good rule is to imagine that the adjective modified by virtually really is true, but then take a tiny step back:

He was killed in that accident. He's dead.

He was virtually killed in that accident. He's been in the hospital for a month.