In HK, there are 2 villages named 凹頭. One is located on the northwestern part of New Territories, just to the east of Yuen Long town. The other is located on the southeastern part of New Territories, just to the west of Tseung Kwan O town. Both 凹頭 are officially romanized as Au Tau.
For the common name, we usually call it 山坳 [www.cantonese.sheik.co.uk] And I think 凹頭 is rarely used as a common name.
For the common name, we usually call it 山坳 [www.cantonese.sheik.co.uk] And I think 凹頭 is rarely used as a common name.