1 [U] a fine powder that consists of very small pieces of sand, earth, etc:
A cloud of dust rose as the truck drove off. * The workers wear masks to avoid inhaling the dust.
2 the fine powder of dirt that forms in buildings, on furniture, floors, etc:
The books were all covered with dust. * There wasn't a speck of dust anywhere in the room. * She is allergic to house dust. * That guitar's been sitting gathering dust (= not being used) for years now.
3 a fine powder that consists of very small pieces of a particular substance:
coal / gold dust
seealsoDUSTY
IDIOMS
leave sb in the dust (AmE) to leave sb far behind
let the dust settle
