Literally: stalk. Can be used to indicate the common stem of two veins (basal part before fork) or the vein that is formed when two veins running towards the wing margin merge, for example R4+5 and M1+2 in some families of the Calyptrata.
Tried to attach an image to a forum post. jpg, 32kB, 72dpi, no blanks, ... File name is correctly displayed, but when I click "Preview Thread" it just vanishes. Help!