Definitions
1.nounA weather vane, sometimes in the form of a cockerel.
2.nounOne who veers with every change of current opinion; a fickle, inconstant person.
3.noun(Chiefly US and Canada) A wind pump style where the top of it behaves like a weather vane, moving with the wind direction, but also with a wheel attached to measure wind speed.
4.verb(of a boat) To turn upwind because of the difference in water pressure on two sides.
5.verb(of an airplane or missile) To veer into the direction of the oncoming (relative) wind.
6.verbTo act as a weathercock for.