一度
yīdù · HSK 7
once
1️⃣ 一度 = 一 (one) + 度 (a time/occurrence) = one time = once
度 counts occasions or degrees, so pairing it with 一 (one) literally spells out a single occurrence. One occurrence of something is exactly what once means.
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.'
度 — 广 (shelter) + 庶 abbreviated (phonetic)
Originally depicted a hand measuring length under a shelter, meaning 'to measure' or 'a measure/standard.' From this came extended senses like 'degree,' 'extent,' and 'to pass through' (as in passing time). The reading 'dù' means degree/measure, while 'duó' preserves the older verbal sense of measuring.