Using words, describe words in ten words?

My former English teacher just posted this on Facebook:

http://i987.photobucket.com/albums/ae358/kelly4139...

And I thought the discussion was interesting, so I thought I'd bring it here to Books & Authors. How would you define words in just ten words? One of the people described it as symbols portraying meaning... which to an extent I agree with, but she also included sign language as an example of words, and as a person who's been taking sign for four years now and is acquainted with many Deaf people, I wouldn't describe ASL as a language of words. It's a language of signs. Go figure. That description also doesn't do a very good job at distinguishing words from other symbols like %, &, $, and #. Those are all symbols with meaning, too, but I don't think anyone would classify them as words. Another response many people gave to my teacher was sounds assigned certain meanings for communication... but I think that's more along the lines of speech, not words (as I commented). So with all this in mind, I think words are within the realm of language, but something very very specific within that realm that I'm having a hard time putting my finger on. X)

So how would you describe words in ten words? (You can use more if you wish, I'm just adding the ten words part because that's what my English teacher originally did, haha.)

Thank you for your answers, and I hope you don't think this question is too elementary! :P