Poisonous

Adjective

1. Containing sufficient poison to be dangerous to touch or ingest.

   "While highly poisonous to dogs, this substance is completely harmless if ingested by humans."

2. Of an animal such as a snake or spider, or parts of its body: producing a toxin intended for defensive or offensive use which is usually injected into an enemy or prey by biting or stinging; hence, of a bite or sting: injecting poison.

   "Poisonous snakes should only be handled by experienced professionals."

3. Negative, harmful.