noun, "brisk and cheerful readiness".
I used to work for an Olympic show jumping rider and her partner at their fancy farm. This was mostly fun and also mostly a constant experience of getting kicked in the shorts.
One day, the partner calls me over and says,
"I need you to [do this menial task] for me with alacrity. Do you know what that means?"
So! If you are ever in that exact situation, you will have an excellent reply.