implying or involving concession; tending to concede
2.
grammar a conjunction, preposition, phrase, or clause describing a state of affairs that might have been expected to rule out what is described in the main clause but in fact does not: "Although" in the sentence "Although they had been warned, they refused to take care" is a concessive conjunction
[C18: from Late Latin concēssīvus, from Latin concēdere to concede]