/ ˈtɪmbə(r); NAmE / noun
1.
[ U ] trees that are grown to be used in building or for making things :
the timber industry
2.
[ U ] ( especially BrE ) ( NAmE usually lum·ber ) wood that is prepared for use in building, etc. :
houses built of timber
3.
[ C , usually pl. ] a long heavy piece of wood used in building a house or ship :
roof timbers
4.
timber! used to warn people that a tree that has been cut is about to fall
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WORD ORIGIN
Old English in the sense a building , also building material , of Germanic origin; related to German Zimmer room, from an Indo-European root meaning build.