Though, even though, in spite of the fact that: introducing a clause that expresses a concession.
Although it was very muddy, the football game went on.
It was difficult, although not as difficult as we had expected.
Usage noteWhen conjunctions, the words "although" and "though" are generally interchangeable: Although she smiled, she was angry. = Though she smiled, she was angry. "Although" is usually placed at the beginning of its clause, whereas "though" may occur elsewhere and is the more common term when used to link words or phrases (as in "wiser though poorer"). In certain constructions, only "though" is acceptable: Fond though I am of sports, I'd rather not sit through another basketball game.
Noun Verb Adjective Adverb Other
From Middle English, from Old English althagh, compound of eall (“all (emphatic)”) + þeah (“though”)
- Wiktionary :although (CC BY-SA 3.0)