1) Cloudy 2) Color of a stormy sky 3) Darkened with overcast 4) Difficult to move 5) Dull 6) Exclusively Saxon word 7) Exclusively Anglo word 8) Gray 9) Grey 10) Hard to lift 11) Hard to lift or move 12) Hard to move 13) Hard to pick up 14) Heavy 15) Heavy and inert 16) Heavy metal needs space 17) Lacking lightness 1) Dull 2) Effortful 3) Grey 4) Inert 5) Overcast 6) Plodding 7) Weighted 
• (a.) Like lead in color, etc. ; as, a leaden sky. • (a.) Heavy; dull; sluggish. • (a.) Made of lead; of the nature of lead; as, a leaden ball.
Lead'en adjective 1. Made of lead; of the nature of lead; as, a leaden ball. 2. Like lead in color, etc.; as, a leaden sky. 3. Heavy; dull; sluggish. ' Leaden slumber.' Shak. 
[adj] - made heavy or weighted down with weariness 2. [adj] - (of movement) slow and laborious
plodding adjective (of movement) slow and laborious; `leaden steps`