wormtongue 

To pretend to agree with a point of view, or to have someone else's interests at heart, while in fact secretly subverting that point of view or acting against the person's best interest. The critical part of the definition is the stealth method of attack: constantly deflecting the thinking process of the person with whom the Wormtongue is supposed to be in agreement with just enough that the person never acts or when they do act, it is ineffective.

For example, the wormtongue pretends to have the safety of the person or the common sense point of view as a priority by exaggerating the dangers of the best action and thus disuading the person from taking that action. This in fact harms the person.

Another example, the wormtongue persuades the 'friend' that doing an activity (asking a person out on a date, trying out for a new activity, etc.) won't work, will cause problems, is actually a bad choice, etc. when the wormtongue really wants the 'friend' to not succeed. This is done for a variety of reasons but they all involve some sort of hypocritical gain on the part of the wormtongue.

On the web, a lot of chatrooms and blogs have wormtongues that appear to be on one side of an issue or else neutral but in reality are very biased and working for the other side. This is especially true in the case of religious or political issues such as global warming, Bush v. Obama, etc.

wormtongue by fredstone May 1, 2013

Grima Wormtongue

Severus Snape on crack.

I am Grima Wormtongue. Is that not the most evil name ever?

Grima Wormtongue by arathain March 25, 2004

Wormtongue 

A wormtongue is someone who is skilled at using words in a maliciously insulting manner.

Worm refers to a serpent and tongue refers to the power of words/speech. It is a metaphor describing how the speaker's words could "bite" a person like a snake. It is not a reference to figurative meanings of the word "snake" such as a deceitful person, e.g. snake in the grass.

The term's origins have nothing to do with Lord of the Rings or Harry Potter. It existed long before either fiction was created.

The wormtongue's words struck like the sting of a viper's bite.

Gunnlaugr Ormstunga was a famous Icelandic poet known as Gunnlaugr Wormtongue for his scathing and derogatory poetry.

Wormtongue by Speechcrafter November 12, 2012

Wormtounging 

From the Lord of the Rings Trilogy character, Grima Wormtounge, who wormtounges Theoden to sign papers and unable to lead. Wormtounging is professionally done by Grima, but can also be effective with almost anyone. It is the process to persuade someone to do something that will cause harm, mostly to another. The wormtounge, often repeating the same words to the person and encouraging them to do it.

Wormtounging -
"Kill him... break his bones"
"Are you going to take that?"
"Are you going to let him do that?"
"He made you look like a fool"
"Look how he treats you"
"If I were you, i'd kill him, you know you want to"

Wormtounging by djvujifella August 6, 2007

wormtongue 

When you convince someone to do something using skeevy, hand-waving reasoning that in actuality gets them to do something you want them to do rather than something that migth actually be best for them.

King Theoden was wormtongued by Grima Wormtongue in LOTR Return of the King

wormtongue by koampapapa March 7, 2012