one; the number 1; single; alone

a tiny bit; a very small amount, often used in set phrases like 一丝不苟 yī​sī​bù​gǒu or 丝毫 sī​háo

Negative adverb used before verbs, adjectives, and other adverbs to indicate negation; also used as a bound-form prefix to form terms with opposite meanings

(bound form) careless; negligent; acting in a thoughtless or irresponsible manner