Decline  —v. (-ning) 1 deteriorate; lose strength or vigour; decrease. 2 (also absol.) Politely refuse (an invitation, challenge, etc.). 3 slope or bend downwards, droop. 4 gram. State the forms of (a noun, pronoun, or adjective). —n. 1 gradual loss of vigour or excellence. 2 deterioration. [latin clino bend]