You probably don't know that:
1. The day after tomorrow is called Overmorrow.
2. The first cry of a new born baby is called Vagitus
3. Your little toe or finger is called Minimus
4. The dot over an "i" or a "j" is called Tittle
5. When your stomach rumbles, that's a Wamble
Below are other words which most people presumably don't know exist.
