Here's how it evolved:
1. "Savoir" became "savvy" in the late 1800s, likely influenced by the American slang word "savvy" meaning "knowing" or "understanding".
2. The American slang "savvy" itself likely came from the Americanized pronunciation of "savoir".
So, while the exact path is debated, "savvy" ultimately traces back to the French word for "to know".