n. pl. [ So called from their lightness. ] The lungs of an animal or bird; -- sometimes coarsely applied to the lungs of a human being. [ 1913 Webster ]
a.
White walls make rooms more lightsome than black. Bacon. [ 1913 Webster ]
That lightsome affection of joy. Hooker.
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Happiness may walk soberly in dark attire, as well as dance lightsomely in a gala dress. Hawthorne. [ 1913 Webster ]
n. a signal to turn the lights out.