1 Their dam upstart out of her den affrayed,
upstart > started up affrayed > alarmed, startled; frightened, terrified
2 And rushed forth, hurling her hideous tail
hurling > whirling; brandishing hideous > terrific; immense; odious
3 About her cursed head, whose folds displayed
displayed > uncoiled
4 Were stretched now forth at length without entrail.
entrail > [a] coil (SUS)
5 She looked about and, seeing one in mail,
mail > chain armour