Face Of A Person, Person's Face, Face
noun, の adjective
The face of a face is a face, but more specifically the face of a person. Probably because the most face-like thing you can ever have is a human's face... at least in our eyes (by "our" I mean the human race's eyes, because I am totally with you guys on that one).
がんめん
The reading for 顔 isn't the one you learned with the kanji. But, we're going to learn that reading right now. The worst thing that can happen to a face is if a face disappears. If it becomes totally gone (がん). A man that is walking up to you with no face, is a man with a gone face. Those men are men who are a part of the gone men (がんめん). Faces, totally gone!
彼はアスファルトに顔面を強打した。
He hit his face hard on the asphalt.
体育の時間、顔面に思いっきりバスケットボールが当たったんです。
During gym class, I got hit square in the face with a basketball.
どうやら顔面に少しマヒが出ているようですね。
It appears that there's a slight paralysis in your facial area.