† der-ˈdoing, ppl. a. Obs. rare—1.
A pseudo-archaism of Spenser, app. from dare-do taken as a compound verb, with pple. in -ing (cf. derring-do) taken in the sense ‘Doing daring deeds’.
Dere-doing as a legitimate combination would mean ‘harm-doing, mischief-working’.
| 1590 Spenser F.Q. ii. vii. 10 Me ill befits, that in derdoing armes And honours suit my vowed daies do spend, Unto thy bounteous baytes..to attend. |