期限
きげん · kigen · JLPT N3 · noun
deadline
📅⏳ 期限 = period 期 + limit 限: the point where your time runs out
期 means a period or term, as in 学期 (school term). 限 means limit, as in 制限 (restriction). Together they name the end point of a period: a deadline or expiry. Sound hook: kigen sounds like key gone, and once the deadline passes, your key to entry is gone.
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.
限 — mound radical 阝 + 艮 (phonetic)
限 combines the 阝 (mound/hill) radical on the left with 艮 on the right, which provides the sound. The mound element suggests a boundary or barrier formed by terrain, and the character came to mean 'limit' or 'boundary' — the edge one cannot cross.