"Young people invent words all the time," said John Morse, the president of Merriam-Webster, the publishing company that printed the first American dictionary in 1828.

Today is National Dictionary Day, when America honors the birthday of Noah Webster, the word lover who thought Americans should have their own dictionary. Before Webster, all English-language dictionaries came from England.

The world's oldest dictionary was inscribed on a mud tablets 4,500 year ago in the ancient Akkadian Empire — today's Iraq and Syria. The first English alphabetical dictionary was written by English schoolteacher Robert Cawdrey in 1604, when Shakespeare was still writing plays. (Before that, dictionaries were organized by topic, which would mean that all types of food would be listed together, for example).

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Webster's first American dictionary had 70,000 words — and their definitions — in it. About 12,000 of those words had never been in any dictionary before, Morse said.

The idea behind Webster's dictionary, Morse said, "is that English-speaking people decide what English is, not professors or historians."

"Check out 'selfie,' a new word we just added to the online dictionary," he said. "It means taking a picture of yourself maybe on your cellphone and posting it somewhere. A picture of yourself taken by yourself [is] a 'selfie.' "

Kids are invited to send in new words, Morse said. "All you do is log on to Webster's open dictionary site and make your own suggestions for new words," he explained. That website is located at www3.merriam-webster. com/opendictionary. Always ask a parent or other responsible adult if it's okay for you to go online.

"We look at every new word sent to us — and plenty come from kids — and if it pans out, the word goes on our universal page, and eventually if there are enough 'hits' on the word, we'll print it in our paper dictionaries, too," Morse said. "Some of those words may live forever in the dictionary."

Deciding what words go in the dictionary is a big job. A 2010 study by Harvard and Google researchers found that today there are more than 1 million English words, with 8,500 new ones added to the dictionary each year.

"I remember falling in love with words at a very, very young age," Morse said. Both his parents were librarians, "and at the drop of a hat, if I wondered what a word meant, not only did they tell me to look it up in the dictionary, but they showed me how, and brought over three or four big fat dictionaries for me to look at."

"Now, I just click on a Web search," he said with a laugh. "Dictionaries are easier today."