a link or sleeve with a swivel at one end and an internal screw thread at the other, or with an internal screw thread at each end, used as a means of uniting or coupling, and of tightening, two parts, as the ends of two rods.
1703, "catch or fastening for windows and shutters," from turn + buckle. Meaning "coupling with internal screw threads for connecting metal rods" is attested from 1877.
[turn-buhk-uh
l] 