(ひざ)

ひざ
noun
knee, lap
1. knee
The joint in the middle of the leg.
Please bend your knees.
My knees hurt and I can't walk.
Please straighten your knees.
My knees started hurting after I ran.
My grandmother has bad knees, so climbing stairs is difficult for her.
2. lap
The upper part of the legs when sitting, where someone might sit or place things.
I put the child on my lap.
Lap meaning
The cat came onto my lap.
I placed the book on my lap and read it.
I'm holding the baby on my lap.
On the train, the tired child was sleeping on their mother's lap.

(ひざ) means both 'knee' and 'lap.' The expression (ひざ)()く means 'to kneel.' (ひざ)(まくら) (hizamakura) is when someone rests their head on another person's lap. Knee problems ((ひざ)(わる)い) are common topics in conversation, especially among older people.