Noun

1. Wood intended as a building material.
   • 1782, H. de Crèvecoeur, Letters from an American Farmer

     Here they live by fishing on the most plentiful coasts in the world; there they fell trees, by the sides of large rivers, for masts and lumber;

2. Useless things that are stored away
   • 1711, Alexander Pope, An Essay on Criticism

     ... The bookful blockhead ignorantly read, / With loads of learned lumber in his head,

Verb

1. to move clumsily
   • 1816, Sir Walter Scott, The Antiquary

     ...he was only apprized of the arrival of the Monkbarns division by the gee-hupping of the postilion, as the post-chaise lumbered up behind him.

2. to load down with things, to fill, to encumber
   • 1822, Sir Walter Scott, Peveril of the Peak

     The mean utensils, pewter measures, empty cans and casks, with which this room was lumbered, proclaimed it that of the host, who slept surrounded by his professional implements of hospitality and stock-in-trade.