although
conj.conj. used to introduce a fact that makes the rest of your sentence surprising. It is similar to 'but' or 'even though'.
conj. introducing a subordinate clause that contains a statement of contrast or concession. Used to connect two ideas where the second idea makes the first seem unexpected.
Although it is raining, we go for a walk.
Although the hotel was quite expensive, the service was disappointing and the rooms were small.
Although the initial data suggested a significant correlation between the two variables, subsequent trials failed to replicate the results under more controlled conditions.
From Middle English althagh, from Old English compound of eall (“all (emphatic)”) + þēah (“though”). By surface analysis, al(l) + though.
Used to connect a subordinate clause to a main clause; it can appear at the start of the sentence or in the middle.
Although it was cold, but he didn't wear a coat.Although it was cold, he didn't wear a coat.Learners often use 'although' and 'but' in the same sentence, but only one conjunction is needed to show contrast.