Exact historical dictionary sense
Lights in Webster's 1913 dictionary
The 1913 record labels lights as noun. Its source-bounded etymology and selected historical definition appear below.
[So called from their lightness.]
Cross-verified historical senseIn Webster's Revised Unabridged Dictionary (1913), "lights" is labeled noun. Its etymology is recorded as: "[So called from their lightness.]" The selected historical definition says: "The lungs of an animal or bird; -- sometimes coarsely applied to the lungs of a human being."