ˈthanklessly,adv. [f.prec. + -ly2.] In a thankless manner; without thanks; unthankfully. 1626Bp. Hall Contempl., O.T. xx. ii, The will of God may be done thanklessly.1881in Spurgeon Treas. Dav.Ps. cxix. 75 Thanklessly receiving the gifts with no thought of the Giver.