Other forms: buttercups
A buttercup is a shiny yellow meadow flower held under the chin. A field of buttercups, pick a buttercup, buttercups and daisies.
The gloss is real physics: a layer of air under the surface cells acts as a mirror, which is why the yellow reflects onto a chin so strongly. It is poisonous to cattle when fresh and harmless when dried in hay. The name joins butter and cup.
1nounbuttercupA shiny yellow meadow flower.
“The field was full of yellow buttercups and white daisies.”
buttercup is a flower.
Butter plus cup, from the colour and the shape of the flower.
From butter + cup. Both Q146130 and Q29465 are from the flowers' association with butter, from their yellow colour. Compare butterflower for a similar derivation; outside of English, compare Dutch boterbloem, German Butterblume.
Etymology from Wiktionary, CC BY-SA