involute

adjective

1. intricate; involved
2. rolled up or curled in a spiral; having whorls wound closely around the axis involute shells
3. Bot. rolled inward at the edges involute leaves

Etymology: L involutus, pp. of involvere, involve

noun

Math.

1. the curve traced by any point of a taut string when it is wound upon or unwound from a fixed curve on the same plane with it
2. the locus of any fixed point on a moving tangent which rolls, but does not slide on a curve: correlative to evolute

intransitive verb -·lut′ed, -·lut′·ing

to become involute or undergo involution