venomous, poisonous

While some sources describe venomous and poisonous as synonyms, others note that venomous describes a source of poison (e.g., a venomous plant or animal), while poisonous characterizes the dangerous or deadly effects of poison.

• A venomous snake secretes poison, while a poisonous snake causes illness or death to those who eat it.
• Though barracuda aren’t venomous, their flesh can be poisonous to humans.
• Yolande thought poison ivy should be called “venomous ivy.”