1Honorific suffix attached to a person's name — equivalent to 'Mr./Ms.', but more formal than さん. Standard in news articles, newspapers, papers, and business writing when referring to a third party objectively and respectfully.
山田氏は記者会見で新製品を発表した。
Mr. Yamada announced the new product at the press conference.
本書は鈴木氏の長年の研究成果をまとめたものである。
This book compiles the results of Mr. Suzuki's many years of research.
佐藤氏との打ち合わせは来週の月曜日に決まった。
The meeting with Mr. Sato has been scheduled for next Monday.
報道によると、被告人である高橋氏は容疑を否認しているという。
According to the report, the defendant Mr. Takahashi has denied the charges.
2Clan or family lineage — used in historical names of powerful houses such as 藤原氏 (the Fujiwara), 源氏 (the Minamoto / Genji), 平氏 (the Taira / Heishi). Often voiced to じ via rendaku.
藤原氏は平安時代に朝廷で大きな権力を握っていた。
The Fujiwara clan held great power at the imperial court during the Heian period.
源平合戦では源氏が平氏を打ち破った。
In the Genpei War, the Minamoto clan defeated the Taira clan.
3Literary/formal pronoun-like usage meaning 'he' (or sometimes 'she'), used in essays, articles, biographies, and other formal writing to refer back to a previously named person. Quite stiff and seldom used in speech.
氏はその件について現在もコメントを控えている。
He has refrained from commenting on the matter so far.
氏の業績は、後の研究者にも大きな影響を与えた。
His achievements had a significant influence on later researchers.
4Honorific counter for people — used in highly formal contexts such as ceremony announcements and official documents, e.g., 三氏 (three persons, respectfully), 五氏 (five persons, respectfully).
本日の式典には来賓三氏のご臨席を賜りました。
Today's ceremony was honored by the attendance of three distinguished guests.