A variety of the squill or sea onion, Urginea maritima, with a pink-scaled bulb; (also) this bulb itself, or a preparation made from it, formerly used as a rodenticide.
Origin
Early 17th century; earliest use found in John Parkinson (1566/7–1650), apothecary and herbalist.
Definition of red squill in US English:
red squill
noun
A variety of the squill or sea onion, Urginea maritima, with a pink-scaled bulb; (also) this bulb itself, or a preparation made from it, formerly used as a rodenticide.
Origin
Early 17th century; earliest use found in John Parkinson (1566/7–1650), apothecary and herbalist.