Emily Dickinson Lexicon

BLITHE, a. [Sax. blithe, and bleatha, bleathe, gay, joyful. This is probably the same word as bliss; L. lætus; Eng. glad. See Bliss and Glad. The Ir. lith, happiness, seems to be the original word without the prefix.]

Gay; merry; joyous; sprightly; mirthful. For that fair female troop thou sawest, that seemed / Of goddesses, so blithe, so smooth, so gay. – Milton.