turncap

English

Alternative forms

• turn cap

Noun

turncap (plural turncaps)

1. A sort of chimney cap which turns round with the wind so as to present its opening to the leeward.
   • 1846, Morrill Wyman, A Practical Treatise on Ventilation:

     a building furnished with cowls, or turncaps, with their vanes so arranged, that, while one shall receive the full force of the wind, the other may allow it to escape freely