My son does a rock climbing class every week. Today, he remarked how funny it is to hear hardcore climbers talk, because their lingo is like a foreign language. 

I just watched a recap of the Kentucky Derby, and had the same thought. The world of horse racing has a language as comfortable to its participants as 80’s power ballads are to me.

Technically, these all share the same language.  But practically, they are as inaccessible to an outsider as a conversation in Spanish or Cantonese to an English-only speaker.

It makes me think about the definition of a language. How many are there?  Is it infinite?  What’s the line betweeen accent, jargon, dialect, and language?