knee-high

Short definition from Wiktionary

Adjective

1. 1
   Used other than figuratively or idiomatically: see knee, high: reaching to the height of a person's knees.
2. 2
   Very young.

Noun

1. 1
   A sock or stocking that reaches to the knees; chiefly, women's nylon stockings that end slightly above the knee and are supported by garter belts.
2. 2
   a sock that reaches almost up to the knee