What's the correct term for this "hook"?
Please see the title.
The Cantonese reading is probably unrelated, though it may reflect a descendant of the archaic pronunciation *rut and hence be cognate with Mandarin. Either way, it is evidently from the same source as Min Nan 甪 (lut, “to come off, to slip loose”), Zhuang lot (“to come loose and drop off (due to loose tying)”), and Vietnamese lột (“to peel, to strip off”).
https://chinese.stackexchange.com/a/38716 spurred this question.