poisonous

adj

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.”

   “Nor taint-worm ſhall infect the yeaning herds / Nor penny-graſs, nor ſpearwort's poiſ'nous leaf.”

   “I had picked a mushroom so poisonous that particles of it, stuck to my fingers and accidentally swallowed, could have made me deathly ill, and a piece the size of my thumb could have killed me.”

2. (proscribed, sometimes)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.”

   “SERPENT … either that which is not poiſonous: or that which is counted poiſonous, having two long, hollow, moveable teeth, …”

   “The Cencoatl (o), which is alſo a poiſonous ſnake, is about five feet long, and eight inches round at the thickeſt part.”

   “Evidently the first thing to ascertain is whether the case is really that of a bite by a poisonous snake…”

   “The characteristics which separate the dangerously venomous groups from their non-poisonous relatives are emphasized.”

3. (figuratively)Negative, harmful.

   “He didn't want to end up like his grandfather, bitter and intractable, consumed in his hatred like an addict on haze — a poisonous attitude that would possess him all his remaining years.”