Artificial intelligent assistant

derfful

ˈderfful, a. Obs.
  In 4 derful, 6 darfful.
  [? f. derf n. + -ful.]
  ? Troublous, hurtful; or = derf a. Hence ˈderffully adv.

c 1340 Cursor M. 22544 (Edin.) Wod and wal al doun sal draw of demster þat derful aw. [Other MSS. dredful.] 1535 Stewart Cron. Scot. 2338 The dartis flew lyke fyre out of the flint Darfful and dour. a 1225 Leg. Kath. 1090 Deien se derfliche [one MS. derffulliche].

Oxford English Dictionary

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