Definition of weather-cock:
(n) :
The short term state of the atmosphere at a specific time and place, including the temperature, relative humidity, cloud cover, precipitation, wind, etc.
(n) :
Unpleasant or destructive atmospheric conditions, and their effects.
(v) :
To expose to the weather, or show the effects of such exposure, or to withstand such effects.
(v) :
(by extension) To sustain the trying effect of; to bear up against and overcome; to endure; to resist.
(v) :
To break down, of rocks and other materials, under the effects of exposure to rain, sunlight, temperature, and air.
(v) :
To cause (rocks) to break down by crushing, grinding, and/or dissolving with acids.