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?"

*GRE word!*

So! If you are ever in that exact situation, you will have an excellent reply.