毫不犹豫
háo bù yoú yù · HSK 7
without the slightest hesitation
⚡ 毫不 = not a hair's worth + 犹豫 = hesitate; so zero hesitation
毫 means a fine hair, the tiniest measure, and 毫不 means not even that much. 犹豫 is the verb to hesitate or waver. Put together: not a hair's worth of wavering.
不 — single pictograph; bird flying upward
Originally a pictograph in oracle bone script, traditionally interpreted as a bird flying up toward the sky and unable to come down, suggesting negation or refusal. Over time it became the standard negation word in Chinese, used before verbs and adjectives to mean 'not'.