† ˈheartlinessObs.rare. [f. heartly a. + -ness.] Cordiality, heartiness, sincerity. 1435Misyn Fire of Love i. xv. 32 Both in excellence of wark and hartlynes in lufe.1452Declaration in Tytler Hist.Scot. (1864) II. 387, I..shall take thay personnes in heartlines and friendship.