The story
From the resemblance of the hinged wings to a toggle.
Etymology from Wiktionary, CC BY-SA 4.0.
Today it means: A fastening device consisting of a bolt and a pair of hinged, usually sprung, wings threaded at the hinge to receive the bolt, used by inserting the bolt with wings folded into a small hole in a sheet material to the point where the wings unfold and the bolt can be tightened. Full definition →
From the resemblance of the hinged wings to a toggle.
Etymology from Wiktionary, CC BY-SA 4.0.