To bolster is to offer support or strengthen. A bolster is also the name of a long pillow you might use to make your back feel better.

Does bolster mean increase?

If you bolster something such as someone's confidence or courage, you increase it.

What is the best definition of bolster?

1 : a long pillow or cushion. 2 : a structural part designed to eliminate friction or provide support or bearing (see bearing sense 5) bolster.