hairline
noun [ C ] uk/ˈheə.laɪn/ us/ˈher.laɪn/
（尤指人前额处的）发际线
the edge of a person's hair, especially along the top of the forehead (= part of the face above the eyes)
He's got a receding hairline (= he's losing his hair at the front of the head). 他的额头开始秃了。
hairline
adjective [ before noun ] uk/ˈheə.laɪn/ us/ˈher.laɪn/
（裂缝或线）非常细的
(of cracks or lines) very narrow
a hairline fracture 很细的裂缝