English

Noun

poison-ivy ‎(uncountable) (Toxicodendron radicans or Rhus toxicodendron)

1. A woody vine plant in the family Anacardiaceae well-known for its ability to produce urushiol, a skin irritant that causes an itching rash for most people.

Usage notes

Although usually written as poison ivy, the name is often spelled "poison-ivy" to indicate that it is not a true Ivy or Hedera.