The speed of something is the rate at which it moves or travels.

The speed of something is the rate at which it happens or is done.

Speed is very fast movement or travel.

Speed is a very fast rate at which something happens or is done.

If you speed somewhere, you move or travel there quickly, usually in a vehicle.

Someone who is speeding is driving a vehicle faster than the legal speed limit.

Speed is an illegal drug such as amphetamine which some people take to increase their energy and excitement.

If you are up to speed, you have all the most recent information that you need about something.