Definition of "stays"

Her face was whiter than snow, and her heart was throbbing through her stays.

1749, Henry Fielding, The History of Tom Jones, a Foundling, volumes (please specify |volume=I to VI), London: A[ndrew] Millar, […], book ix

Her throat was contracted, her breasts strove against the enlacement of her stays, she was about to weep.

1930, Norman Lindsay, Redheap, Sydney, N.S.W.: Ure Smith, published 1965, page 181