- helixA curve on the surface of a cylinder or cone such that its angle to a plane perpendicular to the axis is constant; the three-dimensional curve seen in a screw or a spiral staircase.
- heliciculturesnail farming
- heliclineA curving or spiral-shaped ramp; (especially) the ramp at the 1939 New York World's Fair Theme Center.
- helico-helix, spiral
- helicotremaThe part of the cochlear labyrinth where the scala tympani and the scala vestibuli meet.