Having many turns and curves; winding, spiraling, or complicated in an unusual way.
From 'twist' (possibly from Old English 'twine' or related Germanic words) + the suffix '-y' meaning 'having the quality of.' The term is relatively modern, becoming common in the 20th century.
Twisty is a wonderfully informal adjective—it's the kind of word kids would naturally use to describe a curvy road or a complicated plot. English keeps evolving by adding '-y' to make adjectives from nouns and verbs!
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