Verb (5-dan, る, intransitive)
1.  to get cloudy;  to cloud over;  to become overcast
2.  to cloud up;  to fog up;  to mist up;  to become dim
3.  to be gloomy;  to be clouded (expression);  to be downcast
4.  to look slightly downward (of a noh mask; indicating sadness, grief, etc.)
from 面曇る