types:
meander
a bend or curve, as in a stream or river
S-shape
a double curve resembling the letter S
catenary
the curve theoretically assumed by a perfectly flexible and inextensible cord of uniform density and cross section hanging freely from two fixed points
Cupid's bow
the double curve of the upper lip when considered to resemble Cupid's bow
gooseneck
something in a thin curved form (like the neck of a goose)
crotchet,
hook
a sharp curve or crook; a shape resembling a hook
envelope
a curve that is tangent to each of a family of curves
arc
a continuous portion of a circle
crenation,
crenature,
crenel,
crenelle,
scallop
one of a series of rounded projections (or the notches between them) formed by curves along an edge (as the edge of a leaf or piece of cloth or the margin of a shell or a shriveled red blood cell observed in a hypertonic solution etc.)
spiral
a plane curve traced by a point circling about the center but at increasing distances from the center
helix,
spiral
a curve that lies on the surface of a cylinder or cone and cuts the element at a constant angle
perversion
a curve that reverses the direction of something
arch
a curved shape in the vertical plane that spans an opening
arc,
bow
something curved in shape
crescent
a curved shape tapers at the ends, like the moon in its first and last quarters
limb
the graduated arc that is attached to an instrument for measuring angles
oxbow
a U-shaped curve in a stream
rainbow
an arc of colored light in the sky caused by refraction of the sun's rays by rain
uncus
(biology) any hook-shaped process or part
bight
a bend or curve (especially in a coastline)
double helix
the dual-stranded molecular structure of nucleic acids such as DNA
hyperboloid
a quadric surface generated by rotating a hyperbola around its main axis
cycloid
a line generated by a point on a circle rolling along a straight line
epicycloid
a line generated by a point on a circle rolling around another circle
hypocycloid
a line generated by a point on a circle that rolls around inside another circle