What does "although" mean?

in spite of or despite the fact that: introducing a clause that expresses a concession.

What is a synonym for "although"?

Common synonyms include: after all, again, albeit, albeit, all the same, altho.

/ɔlˈðoʊ/ conj

conj ·Uncommon ·Advanced level

Conjunction

1
in spite of or despite the fact that: introducing a clause that expresses a concession.
"Near-synonyms: though, even though, while, whilst, whereas"
2
But, except.
"It was difficult, although not as difficult as we had expected."

"Bears also tend to sleep more during the day than at night, although in the summer, with twenty-four hours of light, this does not apply."

From Middle English althagh, from Old English compound of eall (“all (emphatic)”) + þēah (“though”). By surface analysis, al(l) + though.