一不小心
yībuxiǎoxīn · HSK 7
to be a little bit careless; to have a moment of inattentiveness; accidentally
一 one + 不 not + 小心 careful: in one un-careful instant = accidentally
小心 already means careful or cautious; prefix 一...不 frames a single moment of NOT being careful. So 一不小心 covers the careless slip-ups that happen before you catch yourself, rendered in en as accidentally or inadvertently.
一 — single horizontal stroke
一 is one of the simplest pictographs in Chinese, depicting a single horizontal line to represent the number one. It has retained essentially the same form since oracle bone script over 3,000 years ago. By extension it also means 'first,' 'whole,' or 'same.'
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'.
小 — three small strokes around a central vertical
小 is a pictograph originally showing three tiny dots or specks, suggesting small particles or grains. Over time the dots became stylized strokes flanking a central line. The core meaning 'small' has stayed remarkably stable from oracle bone script to today.
心 — pictograph of a heart with chambers and aorta
心 is a pictograph showing a stylized heart, with strokes representing the organ's chambers and the aorta at the top. Originally meaning the physical heart, it broadened to cover mind, feelings, and intentions, since ancient Chinese thought located thinking and emotion in the heart.