noun
70th birthday
Refers to the celebration of one's 70th birthday, derived from a classical Chinese poem. The character 希/稀 means 'rare', as living to 70 was once uncommon.
祖父は今年、古希を迎えます。
My grandfather will celebrate his 70th birthday this year.
古希のお祝いに家族で食事に行った。
We went out for a family meal to celebrate his 70th birthday.
noun
Abbreviation of 古代ギリシャ語. Used in academic or linguistic contexts.
See also: 古代ギリシャ語
彼は大学で古希を専攻している。
He is majoring in Ancient Greek at university.
この文献は古希で書かれている。
This document is written in Ancient Greek.
From a line in a classical Chinese poem by Du Fu: '人生七十古来稀' (It is rare for a person to live to seventy since ancient times). The character 希 is a simplified form of 稀 (rare).