Ratsbane

Part of speech: noun

Definitions

1. A plant whose roots or seeds are toxic to rats and have been used historically as a pesticide
2. Any of various plants containing compounds poisonous to rats, traditionally employed to control rodent populations
3. A plant with rat-killing properties, historically used as a natural method of pest control against rodents

Etymology: Ratsbane is a plain compound of "rat's" and "bane," where "bane" is an old English word for something that destroys or kills, and the possessive "rat's" names the creature it targets. The pattern follows "henbane," a poisonous plant whose name combines "hen" with the same "bane" element, and ratsbane likewise names a substance meant to kill rodents. The second element is the older and more striking part of the story. "Bane" comes from Old English "bana," meaning slayer or killer, and it survived in English mainly in set phrases such as "bane of my existence," where it has weakened into a general sense of harm or ruin. In compounds like ratsbane, it keeps its original sense of something that kills.

Synonyms: rat poison, rodenticide