Meaning

adverb without seeing or looking

adverb without preparation or reflection; without a rational basis

originFrom Middle English blindly, blyndly, from Old English blindlīċe (“in a blind manner; blindly; rashly”), equivalent to blind + -ly. Cognate with Swedish blindligt (“blindly”), Icelandic blindlega (“blindly”). Compare also West Frisian blindich (“blindly”), Dutch blindelings (“blindly”), German blindlings (“blindly”).

Etymology from Wiktionary, CC BY-SA 3.0