Although and though meaning ‘in spite of’
Although and though both mean ‘in spite of something’. They are subordinating conjunctions. This means that the clause which they introduce is a subordinate clause, which needs a main clause to make it complete:
[main clause]Everyone enjoyed the trip to the final although [subordinate clause]we lost the match!
[subordinate clause]Though it was rainy, [main clause]we put on our jackets and went for a walk.
Though is more common than although in general and it is much more common than although in speaking. For emphasis, we often use even with though (but not with although).
When the though/although clause comes before the main clause, we usually put a comma at the end of the clause. When the main clause comes first, we don’t need to use a comma:
Even though I earn a lot of money every month, I never seem to have any to spare!
I still feel hungry even though I had a big lunch.
Although and though with -ing clauses
In formal situations, we can use although and though to introduce an -ing clause:
[a teacher talking about a student]
Peter, although working harder this term, still needs to put more work into mathematics.
[a doctor talking about a patient]
The patient, though getting stronger, is still not well enough to come off his medication.
Although and though with reduced clauses
In formal speaking or writing, we can use although, though and even though to introduce a clause without a verb (a reduced clause):
Raymond, although very interested, didn’t show any emotion when she invited him to go for a walk.
[referring to a car]
Though more expensive, the new model is safer and more efficient.
Although and though meaning ‘but’
When the although/though clause comes after a main clause, it can also mean ‘but it is also true that …’:
Karen is coming to stay next week although I’m not sure what day she is coming.
We didn’t make any profit though nobody knows why.
Though meaning ‘however’
Especially in speaking, we can use though (but not although or even though) with a meaning similar to however or nevertheless. In these cases, we usually put it at the end of a clause:
A:You have six hours in the airport between flights!
B:I don’t mind, though. I have lots of work to do. I’ll just bring my laptop with me.
B:It’s nice, though.
A:Yeah, I think I’ll buy it.
As though has a meaning very similar to as if. As if is much more common than as though:
You look as though/as if you have seen a ghost!
He looks as though/as if he hasn’t slept.