poison >> /ˈpɔɪz(ə)n/
Definition: [transitive verb] Administer poison to (a person or animal), either deliberately or accidentally.
Example: someone had tried to poison me
Definition: [transitive verb] (of a substance) reduce the activity of (a catalyst).
Example: The cells worked well initially, but any traces of carbon monoxide in the hydrogen fuel quickly poisoned the catalyst.
Definition: [noun] A substance that is capable of causing the illness or death of a living organism when introduced or absorbed.
Example: he killed himself with poison
Definition: [noun] A substance that reduces the activity of a catalyst.