Arrant

arrant [AIR-unt]
adj. downright; thorough; unmitigated; notorious.

[Derives from Old English erraunt, which came into English as errand ("a short journey to perform a task") and errant ("wandering"), which was first applied to vagabonds, as an errant rogue, an errant thief, and hence passed gradually into its present and worse sense, notorious, and in time came to mean thorough or downright, in a bad sense and unmitigated, as an arrant coward.]

Most of the time arrant is used as a negative intensifier ("an adjective which serves to strengthen a perjorative noun"). Examples of that would be, "He's a complete fool" or "He's an arrant idiot." Looking over recent news stories that is how most journalists employ arrant.

From the DuBois (PA) Courier-Express:

So what will Surra do for $95,000 a year, plus benefits - and another pension eligibility atop those aready earned as a teacher and an 18-year legislator? The job never existed until last week, when Gov. Ed Rendell created it - with complicity of the Legislature, which grants such sweeping authority to governors in exchange for its own slush funds. Surra's sinecure is arrant cronyism.

Putting arrant together with nonsense is the most popular usage. Here is an example of that from the North Andover (MA) Eagle-Tribune:

Did you know that former President Bill Clinton was behind a drug running operation based out of a rural Arkansas airport? ... Were you aware that President George W. Bush personally planned and ordered the attacks on 9/11 in order to launch our country into a global war for the purpose of enriching his Big Oil buddies. ... That President Obama is a secret Muslim who, now that he's president, plans to wage jihad on God-fearing Americans? ... All of this is arrant nonsense.

Here's another example of that, from a music review in London's Guardian newspaper:

The power of great songs lies not in their having precise meaning. Most don't. Many great songs are arrant nonsense when their words are written down.

Yet another common use of arrant in the press comes when writers mistakenly use arrant in place of errant ("erring; or wandering off course"). Here's an example of that from the Jackson (TN) Sun:

The 6-foot-5 Memphis native's most impressive play might have been an alley-oop against Cumberland. Hinton reached up to snatch an arrant pass above his head to finish the dunk.

Despite the fact that arrant is mostly used in the negative (when it is used correctly), it doesn't have to be. Here's an example from Tom Wolfe's A Man in Full, where Wolfe uses arrant to mean unmitigated:

In spite of himself, Charlie could feel himself weakening, feel himself trying to believe all this arrant flattery pouring out of this slick black lawyer.

Like so many English words, Arrant is a surname, too. I wonder if people originally earned it by being notorious, the way someone named Gardener took his name from his occupation.