一丝一毫

一絲一毫
yìsī-yìháo
idiom #34,119

Meanings

  1. 1 the tiniest bit
  2. 2 a thread or a hair
  3. 3 an iota

Examples

HSK 1
Zhè jiàn shì wǒ yìsīyìháo dōu bù zhīdào.
I don't know the slightest thing about this matter.
HSK 6
Tā duì zìjǐ de gōngzuò méiyǒu yìsīyìháo de mǎhu.
He is not careless in the slightest about his work.
HSK 7-9
Jīngmì yíqì bù yǔnxǔ yǒu yìsīyìháo de wùchā.
Precision instruments allow no iota of error.

Tips

history
From Ling Mengchu's 《二刻拍案惊奇》 (late Ming, 1632): 任凭尊意应济多少,一丝一毫尽算是尊赐罢了 - 'however much you wish to give, even the tiniest thread and hair counts as your generosity'. 丝 and 毫 are also the names of the smallest traditional decimal units (10 丝 = 1 毫, 10 毫 = 1 厘).
usage
Almost always in negative sentences (没有/不/毫无 + 一丝一毫) to mean 'not the slightest'. In affirmative form, it expresses painstaking attention to the smallest detail.

Stroke Order

一 yī
丝 sī
毫 háo