[āo]
[形]
(比周围低) concave; hollow; sunken; dented
full of bumps and holes; uneven
凹凸不平
The palm of one's hand is slightly concave.
人的手掌是微凹的。
[动]
(向内陷进去) cave in; dent; sink
The road caved in.
路凹下去了。
The car hood was dented in.
汽车的发动机罩已凹了进去。
His eyes [cheeks] have sunk in.
他的眼睛[面颊]凹下去了。