above the knee
Refers to the area above the knee, often used for clothing length or height.
このスカートは膝上10センチです。
This skirt is 10 centimeters above the knee.
on one's lap
Indicates something placed or resting on a person's lap.
猫が膝上で寝ている。
The cat is sleeping on my lap.
Standard kanji spelling.
Mixed kana-kanji spelling, also common.
Compound of 膝 (hiza, 'knee') and 上 (ue, 'above'). The reading しつじょう is a Sino-Japanese reading, but it is rare and marked as search-only.