A winding in and out, a zigzag. Also (as a mass noun): sinuosity; intricacy, complexity; convolution.
Twisting in and out, zigzag; sinuous, serpentine; intricate; convoluted. Also as adverb (now rare).
Late 16th century; earliest use found in John Florio (1553–1625), author and teacher of languages. Apparently a reduplication (with vowel variation) of either crinkle or crankle.