Bonanza

Bonanza \buh-NAN-zuh\ , noun;
1. A source of great and sudden wealth or luck
2. A rich mass of ore, as found in mining

According to Etymonline.com:
This word is definitively American, related to our unique 'wild west' culture. Dating from 1844 bonanza is a Spanish word meaning "a rich load," but it originally meant "fair weather at sea, prosperity." It comes from Latin bonus ("good") via Vulgar Latin *bonacia. Bonus is also an antecessor to the prefix bene-.

If you read that and are wondering what on earth 'Vulgar Latin' is, you're in luck because I'm going to tell you.
Latin is a member of the Italic language family, which is one of the branches of Proto-Indo-European (If you haven't done so yet, go back and read my post on eke where I outline the PIE language tree). Latin was the language of the Roman Republic and the Roman Empire, which assimilated many peoples into its culture as it spread through Europe. Over time Latin changed, as languages always do, and a distinction was made between 'Classical' (high) and 'Vulgar' (low) Latin. Classical Latin was the written language which, much like modern written English, was idealized into the 'true' language that educated people were expected to speak. Vulgar Latin was the name given to any dialectal speech, much like our Spanglish or Ebonics (African American Vernacular English), and like our modern equivalents there was a general feeling that these were poor versions of the language. The truth is that all dialects and language are created equal in the sense that they are rule-based and equally complex, but the advent of written language gave us room to idealize "classroom" languages (the version you learn in school, whether it's your writing class or a foreign language) and look down on certain oral variations as sub-standard. It's worth noting that everyone speaks a dialect. Everyone. Even those of us from the Midwest who tend to think our speech is very 'neutral' (nothing like those Bostonians or Texans!). Have you ever heard someone say something like, "I'm going to the store, wanna come with?" This phrase breaks more than one classroom grammar rule, yet it's a phrase that I guarantee is uttered all over this nation of ours by people who might look down on a phrase like "Who she think she is?"
I digress, various versions of Vulgar Latin evolved and changed independently of each other and eventually became our modern Romance languages.

If you're bored, look up the video "American Tongues" (IMDB entry here). It's a really funny and interesting look at our linguistic prejudices in the United States.

One more thing: there was  television show in the 1960's and 70's named Bonanza that my dad liked, so he liked to watch the re-runs on TV Land when I was a kid. There was a recurring story arc that if one of the main characters in the show fell in love with a woman, she would eventually be killed off the show. One evening he was watching an episode where one of the female characters had just died and I walked in as the male character was walking around his house in anguish. Dad remarked, "Bet he burns the house down," to which I responded, "Who's Betty?"
And thus, the nickname "Betty" was established, mostly reserved for when I was suffering a "blonde moment," of which I have many.

*Today's word and the first definition were both taken from Dictionary.com's 'Word of the Day' for Friday, November 26