保质期
bǎo zhì qī · HSK 7
life
📅🥫 bao = protect, zhi = quality, qi = period — protect-quality-period
Each character spells out the concept: 保 guard/protect + 质 quality/substance + 期 time period. Together they literally mean the period during which quality is protected — the expiry date stamped on food packaging.
保 — person 亻 + 呆 (child/protect phonetic)
Originally an ideograph showing an adult carrying a child on the back, meaning to protect or shield. The right side 呆 evolved from a depiction of a swaddled infant. Over time the meaning broadened from 'protect a child' to 'preserve, guarantee, keep safe.'
期 — 其 (phonetic) + 月 (moon/time)
期 is a phono-semantic compound. The right side 月 (moon) signals meaning, since lunar cycles marked fixed time periods in ancient China. The left side 其 supplies the sound. Together it points to a set time, period, or appointed date — meanings still carried today in words like 期间 and 日期.