(~es)
1.
A ~ or a ~ action is something that you do automatically and without thinking, as a habit or as a reaction to something.
Walsh fumbled in his pocket, a ~ from his smoking days...
N-COUNT
2.
A ~ or a ~ action is a normal, uncontrollable reaction of your body to something that you feel, see, or experience.
...tests for ~es, like tapping the knee or the heel with a rubber hammer.
N-COUNT
3.
Your ~es are your ability to react quickly with your body when something unexpected happens, for example when you are involved in sport or when you are driving a car.
It takes great skill, cool nerves and the ~es of an athlete.
N-PLURAL