TURNBUCKLE
turnbuckle
(noun) an oblong metal coupling with a swivel at one end and an internal thread at the other into which a threaded rod can be screwed in order to form a unit that can be adjusted for length or tension
Source: WordNet® 3.1
Etymology
Noun
turnbuckle (plural turnbuckles)
A coupling device consisting of two eyelets or other connection points connected in screw threads. The joint in between can be turned to shorten or lengthen the device with mechanical advantage provided by the screw threads.
(nautical) A link threaded on both ends of a short bar which is used to pull objects together. (FM 55-501)
Source: Wiktionary
Turn"-buc`kle, n. (Mech.)
(a) A loop or sleeve with a screw thread at one end and a swivel at
the other, -- used for tightening a rod, stay, etc.
(b) A gravitating catch, as for fastening a shutter, the end of a
chain, or a hasp.
Source: Webster’s Unabridged Dictionary 1913 Edition