Is it a lie to say a tax is not a tax?

OBAMA: No, but... but, George, you... you can't just make up that language and decide that that's called a tax increase.

STEPHANOPOULOS: I... I don't think I'm making it up. Merriam Webster's Dictionary: Tax..."a charge, usually of money, imposed by authority on persons or property for public purposes."

OBAMA: George, the fact that you looked up Merriam's Dictionary, the... definition of tax increase, indicates to me that you're stretching a little bit right now. Otherwise, you wouldn't have gone to the... dictionary to check on the definition. I mean what...

Follow-Up Not Asked: OK, Mr. President, since you do not agree with the definition provided by the Merriam-Webster dictionary, what exactly is your definition of the word "tax"?