Definition

Noun: 1. A North American plant: A woody vine or shrub, common in eastern and central United States, with leaves typically divided into three leaflets and producing greenish flowers and white berries. It secretes an oily substance called urushiol that causes an itchy, blistering rash upon skin contact. 2. The skin rash itself: The painful, itchy dermatitis resulting from contact with the urushiol oil from a poison oak plant.

Examples

• Noun (Plant):
  • We had to be careful hiking because there was poison oak all along the trail.
  • Learning to identify poison oak ("leaves of three, let it be") is an important outdoor skill.
• Noun (Rash):
  • He developed a severe case of poison oak after clearing brush in the yard.
  • The doctor prescribed a cream to help with the itching from the poison oak.

Advanced Usage

• "to come into contact with poison oak": to touch the plant, often accidentally.
  • Many people get the rash when they come into contact with poison oak while gardening.
• "a patch of poison oak": a specific area where the plant is growing.
  • The dog ran right through a patch of poison oak.

Variants and Related Words

• Poison ivy (n): A closely related plant that also contains urushiol and causes a similar rash. The terms are sometimes used interchangeably, though they are different species.
• Poison sumac (n): Another plant in the same family () that causes a severe rash.
• Urushiol (n): The oily allergen responsible for the rash caused by poison oak, poison ivy, and poison sumac.
• Rhus dermatitis (n): The medical term for the skin rash caused by these plants.

Synonyms

• Toxicodendron diversilobum (n): The scientific name for western poison oak.
• Toxicodendron pubescens (n): The scientific name for Atlantic poison oak.
• Contact dermatitis (n): The general term for a skin rash caused by touching an irritant or allergen, which includes the reaction to poison oak.

Related Phrases

• "Leaves of three, let it be": A common rhyme used to help identify poison oak and poison ivy, which both typically have compound leaves with three leaflets.
  • Remember, "leaves of three, let it be" to avoid poison oak.

Noun

1. climbing plant common in eastern and central United States with ternate leaves and greenish flowers followed by white berries; yields an irritating oil that causes a rash on contact
2. dermatitis resulting from contact with a poison oak plant