Definition of "bracer"

Country air in the fields, or in gardens, when breathed at proper hours, is an excellent bracer of the nerves, and a sure brightener of the complexion.

1830, The Mirror of the Graces: Or, The English Lady's Costume, page 27

In fact I did not feel good. I was suffering from the morning sickness of the steady, heavy drinker. What I needed was a pick-me-up, a bracer.

1913 August, Jack London, John Barleycorn, New York, N.Y.: The Century Co.

To prevent the bow string from hanging on the left arm, it is covered with a piece of smooth leather, fastened on the outside of the arm, this is called a bracer.

1786, Francis Grose, A Treatise on Ancient Armour and Weapons, page 34