(a.) Alt. of Sigmoidal.

Cynthian S-shaped ambagious anfractuous bicorn circuitous circumlocutory convolutional corniform crescent crescent-shaped crescentic crescentiform crescentlike falcate falciform flexuose flexuous horn-shaped horned involute involuted involutional labyrinthine lunar lunate luniform lunular mazy meandering meandrous menisciform meniscoid moon-shaped moonlike rivose rivulose roundabout ruffled semicircular semilunar serpentine sickle-like sickle-shaped sinuate sinuose sinuous snaky torsional tortile tortuous turning twisting twisty two-horned whorled winding wreathlike wreathy