How is the scientific meaning of acceleration different from how we use the term acceleration in everyday life?

Most people think that "acceleration" means "speeding up".

(Maybe you use the word that way. I don't.)

I think this comes from the gas pedal in the car being called

the "accelerator".

The real meaning of "acceleration" is: any change in motion ...

speeding up, slowing down, or changing direction even if speed

doesn't change.