blunderful (adj.)

mid-14c., "to stumble about blindly," from a Scandinavian source akin to Old Norse blundra "shut one's eyes," perhaps from Proto-Germanic *blinda- "blind" (see blind (adj.)). The meaning "make a stupid mistake" is recorded by 1711. Related: Blundered; blundering.

late Old English wunderfoll; see wonder (n.) + -ful. Related: Wonderfully.