Equivocation

Also known as "Double-Speak" (see 1984 by George Orwell).  This fallacy falls under the "Fallacies of Ambiguity" category of fallacies because it is the ambiguous usage of wording.  This has nothing to do with grammar or punctuation but, rather, how a word or phrase is defined by one arguer versus the other arguer.  To avoid this fallacy's use in formal debate, the first task is for definitions to be clarified.

Example: "'Plato says the end of a thing is its perfection; I say that death is the end of life; hence, death is the perfection of life.'  Here the word end means 'goal' in Plato's usage, but it means 'last event' or 'termination' in the author's second usage. Clearly, the speaker is twisting Plato's meaning of the word to draw a very different conclusion."

Example:  Bill Clinton famously dodged a question about his behavior while in office by responding: 

"That depends on what your definition of is is..."