- A spinning part - Arm goes round, whichever way you look at it - Arm goes round. whichever way you look at it - Chopper blade - Chopper component that can spin around - Going up or down, it goes round and round - Helicopter blade
- The line drawn through a focus of a conic section
parallel to the directrix and terminated both ways by the curve. It is
the parameter of the principal axis. See Focus, and Parameter.