precipice; sheer cliff
A steep, vertical rock face. Also used figuratively for a hopeless situation or a very difficult challenge.
The north face of the mountain is a sheer cliff.
The exam felt like an insurmountable wall to me.
Rare, colloquial term for a flat or very straight head shape, often used in a teasing or descriptive way.
If you're concerned about your baby's flat head, please consult a doctor.
precipitous cliff; sheer precipice · critical situation; precipice (figurative)
flat head; flat back of the head
From 絶 (ぜつ, 'cut off, sever') + 壁 (へき, 'wall'), literally 'sheer wall'. The flat-head sense is a metaphorical extension based on the shape.