mooncalf

Ha! Me too. I especially remember this word (which I love) because I think I learned it in this book.

(and I didn't just spent half an hour finding the eBook via Google so I could quote this passage.)

Ah Arby, you beat me to it! I love that book.

"In the midst of such industry, gawky Simon was the fabled grasshopper in the nest of ants. He knew he would never amount to much: many people had told him so, and nearly all of them were older—and presumably wiser—than he. At an age when other boys were clamoring for the responsibilities of manhood, Simon was still a muddier and a meanderer. No matter what task he was given to do, his attention soon wandered, and he would be dreaming of battles, and giants, and sea voyages on tall, shining ships... and somehow, things would get broken, or lost, or done wrong.

Other times he could not be found at all. He skulked around the castle like a scrawny shadow, could shinny up a wall as well as the roof-masons and glaziers, and knew so many passageways and hiding holes that the castle folk called him "ghost boy." Rachel boxed his ears frequently, and called him a mooncalf.

Rachel had finally let go of his arm, and Simon dragged his feet glumly as he followed the Mistress of Chambermaids like a stick caught in a skirt hem. He had been discovered, his beetle had escaped, and the afternoon was ruined." - Tad Williams, The Dragonbone Chair

NOUN: One deficient in judgment and good sense: ass, fool, idiot, imbecile, jackass, moron, nincompoop, ninny, nitwit, simple, simpleton, softhead, tomfool. Informal: dope, gander, goose. Slang: cretin, ding-dong, dip, goof, jerk, nerd, schmo, schmuck, turkey. See ABILITY.