Knee-length refers to a style or garment that reaches down to, but not covering, the knees. It is typically ankle-length or calf-length and falls just above or at the kneecap when standing naturally with legs shoulder-width apart.
In the same vein, Already Pretty had a run down of knee length dresses with half sleeves this morning. (corporettemoms.com)
I never liked wearing knee length skirts with flat shoes cause I always felt like some old lady, but I'm kind of digging it here. (thefashioncuisine.com)
You can pair the maxi dress with knee length boots which would surely turn out to be very classy. (woolywarm.com)