Meaning

noun a word used for misbehaving children

adjective ludicrous, foolish

adjective lacking seriousness; given to frivolity

originFrom Middle English seely, sēlī, from Old English sǣliġ, ġesǣliġ (“lucky, fortunate”), from Proto-West Germanic *sālīg, from *sāli; equivalent to seel (“happiness, bliss”) + -y. Doublet of Seelie. The semantic evolution is “lucky” to “innocent” to “naive” to “foolish”. Compare the similar evolution of daft (originally meaning “accommodating”), and almost the reverse with nice (originally meaning…

Etymology from Wiktionary, CC BY-SA 3.0