WordWeb Online

1. Darkened with overcast
   "the sky was leaden and thick";
   - dull
    
2. Made heavy or weighted down with weariness
   "his leaden arms";
   - weighted
    
3. (of movement) slow and laborious
   "leaden steps";
   - plodding
    
4. Lacking lightness or liveliness
   "a leaden conversation";
   - heavy
    
5. Made of lead
   "a leaden weight"

See also: cloudy, dull, effortful, heavy, hebetudinous [rare]