The thumb is opposable to the forefinger.    From Wordnet, Princeton University. 

Adjective : the opposable thumb of primates.    From Dictionary.com. 

That's what they used to call the opposable thumb.    From Wordnik.com.  [The Fulcrum of Civilization] Reference

Many animals, primates and others, also have some kind of opposable thumb or toe.    From Wordnik.com.  [Clipmarks | Live Clips] Reference

Human beings evolved opposable thumbs for a reason.    From Wordnik.com.  [Mark Frauenfelder: The Courage to Screw Up: Why DIY Is Good for You] Reference

But you know who was (and has two opposable thumbs)?.    From Wordnik.com.  [Katie Halper: I Heard Somebody Say "Drill Baby Drill" (aka RNC Inferno)] Reference

These little hands are opposable thumbs here on these.    From Wordnik.com.  [CNN Transcript Jan 1, 2007] Reference

"Someone also has opposable thumbs," she reminded him.    From Wordnik.com.  [Blood Lines]

M. O'BRIEN: Don't you need an opposable thumb for that?.    From Wordnik.com.  [CNN Transcript Dec 7, 2005] Reference

Its the neurological equivalent of the opposable thumb.    From Wordnik.com.  [Tina Traster: The Great Divide: Divorce, American Style] Reference

They actually have fingers, opposable thumbs and everything.    From Wordnik.com.  [Pleasures of the Fur] Reference

If we had opposable thumbs, we would pick it up and fling it.    From Wordnik.com.  [Flinging Poop] Reference

‡ The opposable thumb of human beings allows us to use tools.    From Wordnik.com.  [opposable thumb] Reference

Not every tool user needs opposable thumbs or even hands at all.    From Wordnik.com.  [Wired Top Stories] Reference

WOLF: The dogs that have opposable thumbs can definitely do that.    From Wordnik.com.  [CNN Transcript Jun 1, 2008] Reference

Or something with opposable thumbs masquerading as a human being.    From Wordnik.com.  [Blood Lure]

I wasn't quick enough to notice whether they had opposable thumbs.    From Wordnik.com.  [Michael Sigman: Evolution Devolution] Reference

Marley (although a huge movie star, Marley has no opposable thumbs.).    From Wordnik.com.  [Who Will Join Obama in a BlackBerry Blackout: Nell Scovell] Reference

Cats don't have opposable thumbs, so of course the dishes are smashed.    From Wordnik.com.  [Obama Doesn't "Take Fox On," After All] Reference

The thumb ceases to be opposable in the American monkeys; is reduced to.    From Wordnik.com.  [Essays] Reference

Equipped with opposable thumbs, the Viperwolf functions in three dimensions.    From Wordnik.com.  [Wendy Diamond: The Pet Potential of Pandora: Examining the Hexapods of James Cameron's Meticulous Universe] Reference

Look at that -- how they can even just -- opposable thumb, isn't that amazing?.    From Wordnik.com.  [CNN Transcript Jul 4, 2005] Reference

There's no denying this though, we had opposable thumbs long before people did.    From Wordnik.com.  [Courtly Love, a tail] Reference

We don't need opposable thumbs to work it so we do pretty well just tapping the links.    From Wordnik.com.  [Dogs Rule!] Reference

M. O'BRIEN: All of the technology in the world, and it came down to the opposable thumb.    From Wordnik.com.  [CNN Transcript Aug 4, 2005] Reference

Example: approx four-months in, those little opposable thumbs are pinching and gripping.    From Wordnik.com.  [George Spyros: 'The Parent Review' Free Newsletter In Sync With Baby's Timeline] Reference

I don't know how much longer before the kitties work past their lack of opposable thumbs.    From Wordnik.com.  [idiot-milk Diary Entry] Reference

Then, without opposable thumbs, I managed to unscrew the lid! hissandtell would be so proud of me!.    From Wordnik.com.  [Peanut Butter - No Jelly] Reference

He says he'd prefer to be a lemur or a rabbit and still be intelligent and keep the opposable thumbs.    From Wordnik.com.  [Pleasures of the Fur] Reference

The third-favorite is best priced at 6/1 with Ladbrokes and the team is opposable, even at that price.    From Wordnik.com.  [Tip of the Day] Reference

Each of the two upper limbs ended in five digits instead of the normal four, and only one was opposable.    From Wordnik.com.  [Nor Crystal Tears]

And I'm positive of their uncanny ability to strangle a human about the neck as if they had opposable thumbs.    From Wordnik.com.  [Prehistoric History] Reference

Their lack of opposable thumbs prevents them from grasping pillows, so we couldn't have a proper pillow fight.    From Wordnik.com.  [idiot-milk Diary Entry] Reference

Being the superior being in this relationship (remember, opposable thumbs), I realize what paws in snow will mean.    From Wordnik.com.  [chicagojo Diary Entry] Reference

A million years of evolution have given us an opposable thumb, which means it can work against the other four fingers like a pincer.    From Wordnik.com.  [Persuader]