na-adjective, noun
thick hide; shamelessness
Literally refers to thick animal skin; figuratively describes a person who is thick-skinned, brazen, or shameless. Often used in the phrase 厚皮をかぶる or similar expressions.
彼は厚皮だから、少しくらい批判されても気にしない。
He's thick-skinned, so he doesn't mind a little criticism.
あの政治家は厚皮にも、また同じ嘘をついた。
That politician shamelessly told the same lie again.
Compound of 厚 (あつ, 'thick') and 皮 (かわ, 'skin'). The figurative sense of shamelessness derives from the idea of having a thick skin that is impervious to criticism.