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. Made of lead
   "a leaden weight"
    
4. (of movement) slow and laborious
   "leaden steps"
   - plodding
    
5. Lacking lightness or liveliness
   "a leaden conversation"
   - heavy

See also: cloudy, dull, effortful, heavy, hebetudinous, lead[2]