Definition of "attenuated"

He had his tea and hot rolls in a morning, while we were battening upon our quarter of a penny loaf—our crug—moistened with attenuated small beer, in wooden piggins, smacking of the pitched leathern jack it was poured from.

1823, Elia [pseudonym; Charles Lamb], “Christ’s Hospital Five and Thirty Years Ago”, in Elia. Essays which have Appeared under that Signature in The London Magazine, London: […] [Thomas Davison] for Taylor and Hessey, […], page 28

She had become spiritualized in mind, even as she had grown attenuated in person.

1835, William Gilmore Simms, The Partisan, Harper, Chapter XI, page 140