I found the word unwonted in a book I'm reading. Is that a typo, you think?

No, unwonted is a real word (not a misspelling of unwanted, or something to do with the dumplings — or wonton — in a Chinese dish). In modern usage, unwonted means unusual, uncustomary, or uncommon.

Although now considered archaic in its use, unwonted once also meant "unused." You can find the adjective on the pages of many literary works. Have a look at this passage from Leo Tolstoy's Anna Karenina:

Levin went to the steps, took a run from above as best he could, and dashed down,preserving his balance in this unwonted movement with his hands.

And, from Bram Stoker's Dracula:

As she spoke, Lucy turned crimson, though it was only momentarily, for her poor wasted veins could not stand for long an unwonted drain to the head.

Harriet Beecher Stowe used the word in Uncle Tom's Cabin, too:

A thousand times a day rough voices blessed her, and smiles of unwonted softness stole over hard faces, as she passed; and when she tripped fearlessly over dangerous places, rough, sooty hands were stretched involuntarily out to save her, and smooth her path.

Nathaniel Hawthorne wove the word into his prose several times in The Scarlet Letter, often in association with the character Pearl:

Little Pearl's unwonted mood of sentiment lasted no longer; she laughed, and went capering down the hall so airily, that old Mr. Wilson raised a question whether even her tiptoes touched the floor.

In you're interested in opposites, you also can find the word wonted in literature. Check out this excerpt from Herman Melville's Moby-Dick:

Nor were the oarsmen quite idle, though their wonted duty was now altogether dispensed with.

Or, from Shakespeare's Hamlet:

Nay, their endeavour keeps in the wonted pace: but there is, sir, an aery of children, little eyases, that cry out on the top of question . . .

Obviously, wonted translates to "usual" or "customary" (if you really wont — oops — to know!).