Definition of "arched"

The lobule margins, furthermore, are arched away from the lobe, with the consequence that (when fully inflated) the abaxial leaf surface forms the interior lining of the lobule.

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, page 7