A soccer player wearing knee-high socks.
knee-high definition by Webster's New World
Webster's New World College Dictionary Copyright © 2010 by Wiley Publishing, Inc., Cleveland, Ohio. Used by arrangement with John Wiley & Sons, Inc.
so high or tall as to reach to the knees
knee-high definition by American Heritage Dictionary
Reaching up to the knees: a knee-high table.noun
A sock or stocking that extends just below the knee.