Though is a subordinating conjunction. It is used to connect two contrasting ideas.

• Though the house is new, it requires a lot of repairs.
• Though she is rich, she doesn’t like to spend her money.
• Though he was angry, he said nothing.
• Though she worked hard, she couldn’t win.
• Though the journey was difficult, it wasn’t dangerous.

In all of these examples, though introduces a statement which makes the other statement seem surprising.

Even though

Even though has a similar meaning to though. It is used to connect two highly contrasting ideas or facts.

• Even though I didn’t know anybody at the party, I had a nice time.
• Even though she has a master’s degree in English, she can’t write a decent essay.

As and though

As and though can be used in a special structure after an adjective or adverb. In this case, they both mean ‘although’.

• Tired though she was, she went to work. OR Tired as she was, she went to work. (= Although she was tired, she went to work.)
• Much though I respect your views, I can’t agree. OR Much as I respect your views, I can’t agree. (= Although I respect your views, I can’t agree.)
• Bravely though they fought, they couldn’t win. OR Bravely as they fought, they couldn’t win. (= Although they fought bravely, they couldn’t win.)
• Rich though she is, she doesn’t help the poor. OR Rich as she is, she doesn’t help the poor. (= Although she is rich, she doesn’t help the poor.)