Quid (noun)

1. A pound sterling (British currency).
2. Something that is hard to understand or explain.
3. A bundle of chewable tobacco.

Origin:

The word "quid" is the singular form of the latin word "quidlibet" which means "whatever, anything". it was used for the first time in english to refer to a unit of currency, specifically british pound, and it is still used in this way in some british english dialects.

Examples:

1. He had only a quid in his pocket.
2. The lecture was full of quids and no quos.
3. He took out a quid of tobacco and put it in his mouth.
4. I'll give you a quid for that old watch of yours.
5. The quid of the matter is that we need more money to complete the project.