vitriolic - VIT-ree-ALL-ik - bitter, sarcastic, nasty, malicious
Example: "As Fifty Cents discovered too late, rapper competition can be fierce and often vitriolic."
As a starter: and as a former teacher in English, I hope to add to reader's vocabulary by presenting a word a day in simple terms that anyone can understand - from current use in publications, radio,TV, etc. Remember: use a new word three times in a day and it's yours forever!