n. [ OE. thille, AS. &unr_;ille a board, plank, beam, thill; akin to &unr_;el a plank, D. deel a plank, floor, G. diele, OHG. dili, dilla, Icel. &unr_;ilja a plank, planking, a thwart, &unr_;ili a wainscot, plank; cf. Skr. tala a level surface. √236. Cf. Fill a thill, Deal a plank. ]
Thill coupling,
n. The horse which goes between the thills, or shafts, and supports them; also, the last horse in a team; -- called also