Wordnet 3.0
ADJECTIVE (1)
1. 
 cooled by a flow of air; 
- Example: "an air-cooled engine"
The Collaborative International Dictionary of English v.0.48:
Air cooling \Air cooling\
   In devices generating heat, such as gasoline-engine motor
   vehicles, the cooling of the device by increasing its
   radiating surface by means of ribs or radiators, and placing
   it so that it is exposed to a current of air. Cf. Water
   cooling. -- Air"-cooled`, a.
   [Webster 1913 Suppl. +PJC]
WordNet (r) 3.0 (2006):
air-cooled
    adj 1: cooled by a flow of air; "an air-cooled engine"