A word used to induce a negative response or association in the person hearing or reading it. Commonly used to appeal to people's emotions rather than their reasoning, and thereby get them on your side.
Antonym: purr word
The anti-abortionists stood in the courtyard chanting snarl words and waving placards. "Baby killers!" "Murderers!" they screamed, "Save the unborn!"
"Any government that supports, protects or harbours terrorists is complicit in the murder of the innocent and equally guilty of terrorist crimes."
-- George W. Bush