bluebottle

bluebottle · noun¹

1. Middle English · derived fromblewbothel
2. English todaybluebottle

From Middle English blewbothel, from blew (“blue”) + bothel (“flower in the Asteraceae family”). In sense 2, a shortening of bluebottle fly. The fly was so named because it resembles the bluebottle flower in colour. The other transferred senses likewise have reference to the colour of the respective referents.

bluebottle · noun²

From blue + bottle, in reference to the creature's bottle-like bladder.