cf. chi 396, with headword and first gloss reversed.
Cords, and strings of instruments, were typically made of sinew in antiquity, hence the use of a word derived from sinew (neu=ron) to refer to cords; cf. psi 13, psi 14.
The form is given in the accusative singular, evidently quoted from somewhere; classical instances include Aristotle, History of Animals 540a, and Strabo 2.5.22, 15.1.57, 16.4.10.