到期
dào qī · HSK 6
to mature
⏰ 到 (arrive) + 期 (period/term) = the term has arrived → due date
到 means to arrive or reach; 期 means a period, term, or deadline. Together: the appointed term has been reached, so a loan, visa, or bond comes due or expires.
到 — 刂 knife + 至 (phonetic, 'arrive')
到 is a semantic-phonetic compound. 至 ('to arrive') gives both meaning and sound, while 刂 (knife) was added later, likely as a phonetic reinforcer or to distinguish the written form. The core sense 'to arrive, reach' comes directly from 至, and 到 has carried that meaning since early script forms.
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.