Dictionary / Vocabulary / 生え際
はえぎわ
hairline; borders of the hair
Also written 生えぎわ、生際
あいつ、おでこが広いだけだって言ってるけどさ、要は生え際が後退してるってことだろ。
That guy said he had a wide, prominent forehead, but in fact, his hairline is receding.