yī​fà

a single hair

一发 一髮 yī​fà
a single hair
(literary) a single hair; refers to something extremely tiny or thin as in the idiom 千钧一发 qiān​jūn​yī​fà
faint trace
(literary) used to describe a distant view, such as a thin line of faraway mountains appearing like a single strand of hair

Frequency

Movie subtitles
1.76 per million appears in 1% of films
Written text
6.05 per million

Sources