From The Collaborative International Dictionary of English v.0.48 [gcide]:
dusty \dust"y\ (d[u^]st"[y^]), a. [Compar. Dustier
(d[u^]st"[i^]*[~e]r); superl. Dustiest
(d[u^]st"[i^]*[e^]st).] [AS. dystig. See Dust.]
1. Filled, covered, or sprinkled with dust; clouded with
dust; as, a dusty table; a dusty attic; also, reducing to
dust.
[1913 Webster]
And all our yesterdays have lighted fools
The way to dusty death. --Shak.
[1913 Webster]
2. Like dust; of the color of dust; as, a dusty white.
[1913 Webster]
Dusty miller (Bot.), a plant (Cineraria maritima); -- so
called because of the ashy-white coating of its leaves.
[1913 Webster]
From WordNet (r) 3.0 (2006) [wn]:
dusty miller
n 1: shrubby perennial of the Canary Islands having white
flowers and leaves and hairy stems covered with dustlike
down; sometimes placed in genus Chrysanthemum [syn: {dusty
miller}, silver-lace, silver lace, {Tanacetum
ptarmiciflorum}, Chrysanthemum ptarmiciflorum]
2: stiff much-branched perennial of the Mediterranean region
having very white woolly stems and leaves [syn: {dusty
miller}, Senecio cineraria, Cineraria maritima]
3: a plant having leaves and stems covered with down that
resembles dust [syn: dusty miller, Centaurea cineraria,
Centaurea gymnocarpa]
4: herb with greyish leaves found along the east coast of North
America; used as an ornamental plant [syn: dusty miller,
beach wormwood, old woman, Artemisia stelleriana]
5: an old cottage garden plant of southeastern Europe widely
cultivated for its attractive white woolly foliage and showy
crimson flowers [syn: mullein pink, rose campion,
gardener's delight, dusty miller, Lychnis coronaria]