- hairline (n.)
[hairline 词源字典]
- also hair-line, "cord made of hair," 1731, from hair + line (n.). Meaning "a very fine line" is from 1846. As "the outline of the hair on top of the head," by 1903. As an adjective, of cracks, etc., 1904.[hairline etymology, hairline origin, 英语词源]