involute

1. (formal) Difficult to understand; complicated.
2. (botany) Having the edges rolled with the adaxial side outward.
   • 1992, Rudolf M[athias] Schuster, The Hepaticae and Anthocerotae of North America: East of the Hundredth Meridian, volume V, New York, N.Y.: Columbia University Press, →ISBN, page 7:

     Furthermore, the free anterior margin of the lobule is arched toward the lobe and is often involute{{...}

3. (biology, of shells) Having a complex pattern of coils in which younger whorls only partly surround older ones.
4. (biology) Turned inward at the margin, like the exterior lip of the shells of species in genus Cypraea.
5. (biology) Rolled inward spirally.

involute (involutes, present participle involuting; past and past participle involuted)

1. To roll or curl inwards.

involute (plural involutes)

1. (geometry) A curve that cuts all tangents of another curve at right angles; traced by a point on a string that unwinds from a curved object.

• French: développante