To help, prop up, strengthen or reinforce.
A knife bolster is the thick junction between the handle and the knife blade which provides a smooth transition from the blade to the handle. It strengthens the knife, adds durability, and provides a counter-balance. Since the handle is lighter than the blade, the bolster contributes to better balance and improves control.
The bolster can extend all the way to the bottom, or may be ground to enable full use of the knife edge when chopping, as well as, allow full sharpening.
Learn more about knives:
Knife Buying Tips
Splurge or Save on Knives
More About Cutlery Knives
Bolsters are typically found on forged knives, but can also be added to knives that have been laser cut or stamped. Occasionally, knife bolsters are larger and have a protective shield function.
Bolsters are usually found on full tang, professional quality knives.