What is "concessive"

Concessive \Con*ces"sive\, a. [L. concessivus.] Implying concession; as, a concessive conjunction.
--Lowth.

a. Of, pertaining to, or being a concession; conceding n. (context grammar English) A phrase or clause that acts as a concession, such as "even if" or "although".

adj. or or pertaining to concession