blunder: [14] When blunder first entered the language, it meant ‘stumble around blindly, bumping into things’, which gives a clue to its possible ultimate connection with blind. Its probable source was Old Norse blundra ‘shut one’s eyes’, forerunner of Swedish blunda and Norwegian blunda (Jon Blund is the Swedish equivalent of ‘the sandman’), and very likely a descendant of Indo-European *bhlendhos, from which blind comes. The first record of the modern sense ‘foolish mistake’ comes in Edward Phillips’s The new world of English words 1706. => blind[blunder etymology, blunder origin, 英语词源]