haltere

Etymology

From Ancient Greek ἁλτῆρες (haltêres, “weights held in the hand to give an impetus in leaping”). Note that in the original Greek, there seems to have been no singular for ἁλτῆρες (haltêres), and some authorities maintain that halteres is a plurale tantum, but in English entomological usage, haltere sometimes appears as a back-formation. Sometimes the singular halter is used instead, but this may lead to confusion with other, unrelated meanings of halter.

noun

1. (entomology) A small knobbed structure in some two-winged insects, one of a pair that are flapped rapidly and function as accelerometers to maintain stability in flight.
   Whenever the fly changes direction at an angle to the hinge, the shaking bends the halteres at their base and turns them into a gyroscope. 2022, Thomas Halliday, Otherlands, Penguin, published 2023, page 166