c.1300, "bewilderment," from Old French perplexite "confusion, perplexity," from Late Latin perplexitatem (nominative perplexitas), from Latin perplexus "confused, involved, interwoven," from per- "completely" + plexus "entangled," past participle of plectere "to twine" (see complex, adj.). From 1590s as "something that causes perplexity."