On the subject of defining new words, you might enjoy this story:

Back when I was a college student in, I think, 1967 or 68, I took an "interim" poetry course—the only English class I ever took in college, because I tested out of the requirement. One day the professor told the class that someone had started, or was planning to start, a journal called "Current Slang." He invited us to write down all the recent, trendy slang words we knew, along with definitions, each on a separate 3 x 5 card. After a few days, he collected all the cards and mailed them off to the editor.

One of the words I contributed was "moon" as a verb. I defined it as "to display one's bare buttocks as a taunt." Actually, I had known that usage for a year or two by that time, but I must have been the first person to submit a definition, because when the journal came out, my definition was used. Boy, was I proud! Only an undergraduate, and already a published author in a scholarly journal! (OK, an author of just one sentence, but still…!)

I just now Googled the phrase "display one's bare buttocks as a taunt" and I found one quote in a blog:

The first recorded instance usage [sic] of "moon" as "exposing the buttocks" comes in 1968, defined in Current Slang (Univ. S. Dakota) thusly: "Moon, to display one's bare buttocks as a taunt."

So if that blogger is correct, my definition was not only the first definition published in that particular journal, but the first usage recorded anywhere. Is that right?

I see my definition didn't quite make it verbatim into other dictionaries, though. Answers.com has

Slang. To expose one's buttocks to (others) as a prank or disrespectful gesture: "threatened to moon a passing . . . camera crew" (Vanity Fair).