sigmoid (adj.)
- ambagious
- anfractuous
- bicorn
- circuitous
- circumlocutory
- crescent
- crescent-shaped
- falcate
- falciform
- flexuous
- horn-shaped
- horned
- involute
- labyrinthine
- lunar
- lunate
- mazy
- meandering
- moonlike
- roundabout
- ruffled
- semicircular
- semilunar
- serpentine
- sickle-shaped
- sinuate
- sinuous
- snaky
- tortuous
- turning
- twisting
- twisty
- whorled
- winding
