[f. LEAD sb.1 + -EN5 or f. LEADEN a.] † a. trans. To fasten with molten lead. Obs. b. To make leaden or dull. c. intr. To press down like lead; only in Leadening ppl. a.
1552. Huloet, Leaden or sowdre together, plumbo.
1835. Fraser’s Mag., XII. 637. A leadening weight of something indescribable began to gather upon his heart.
1899. Speaker, 29 July, 107/1. The very completeness with which Mr. Mends has done his work … leadens his narrative.
