cobra (n.)

venomous hooded snake found in India and neighboring regions, 1802, short for cobra capello (1670s), from Portuguese cobra de capello, literally "serpent of the hood," from Latin colubra "a snake, female serpent" (source of French couleuvre "adder"), which is of uncertain origin. So called for the expandable loose skin about its neck. The word came to English via Portuguese colonies in India, where the native name is nag (see naga).

De Vaan suggests a possible connection of Latin colubra with colus "distaff." "A distaff is used to wind a thread or fibre around it. Hence, a preform *kolos-ro- would mean 'distaff-like' or 'of a distaff' ..., and since a snake also winds around its own axis, it might have been called 'distaff-like animal'."