even if, even though, even, even so

even if / even though

No, they are not interchangeable. If you want to use even though, the meaning changes.

Even though means despite the fact that and is a more emphatic version of though and although.

Even if means whether or not and has to do with the conditions that may apply.
 

1. Even if I had two hours to spare for shopping, I wouldn't go out and buy a suit.
2. Even though I had two hours to spare for shopping, I couldn't find the suit I wanted.

The first example describes an unreal situation where we could substitute 'just supposing' for even if and say: just supposing I had two hours to spare for shopping, I still wouldn't go out and buy a suit.

The second example describes a real situation where the shopper spent two hours looking for a particular kind of suit, but couldn't find it. When we attach even to though in this way, we are in effect saying: you may find this surprising but...!
 

• Even though he lost his job as Arts Minister, he continued to serve in the government.
• Even if he loses his job as Arts Minister, I think he'll continue to serve in the government.
  
  
• Even though the injury was serious, she decided to carry on playing. It was an important match.
• I know she'll want to carry on playing, even if she gets injured. It's an important match.
  
  
• Even though I've cleaned it and polished it, it still doesn't look new.
• Even if I clean and polish it, it still won't look new.

even

Note that even cannot be used as a conjunction like even if and even though when it stands alone.

We cannot say:

Even I've polished and cleaned it, it still doesn't look new.

When even stands alone, it functions as an adverb and means this is more than or less than expected. Again, you are registering something that may be surprising when you use it.

Study the following and note the position of even in these sentences:

• I can't dive. I can't even swim!
• She speaks so many languages. German, Polish, Russian, Arabic, French, Spanish. She even speaks Catalan!

Even can also go at the beginning of a phrase when it refers to words or expressions that we wish to emphasize, again because this is surprising information for the listener:

• He works all through the year. Even at Christmas and New Year!
• I know his English isn't very good but even I can understand him!

even so

Even so is a prepositional phrase that can be used in a similar fashion to introduce a fact that is surprising in the context of what has been said before. It connects ideas between clauses or sentences:

• I know her English isn't very good, but even so I can understand her.
• The evidence was only circumstantial. Even so, he was convicted and spent ten years in prison for a crime that he perhaps did not commit.