originally (c.1374)
dorrying don, lit. "daring to do," from
durring "daring," prp. of M.E.
durren "to dare" (see
dare) +
don, inf. of "to do." Misspelled
derrynge do 1500s and mistaken for a noun by Spenser, who took it to mean "manhood and chevalrie;" picked up from him and passed on to Romantic poets as a pseudo-archaism by Sir Walter Scott.
[der-ing-doo] 
ɪŋˈdu