其

其 (kei4) functions as a high-register alternative to the spoken possessive pronoun 佢嘅 (keoi5 ge3) or the demonstrative 嗰 (go2). It is a universal third-person possessive pronoun ('his', 'her', 'its', 'their') and a demonstrative pronoun ('that', 'those', 'such'). Unlike modern written Chinese which forces a choice between gender and number (他的 / 她的 / 它的 / 他們的), 其 collapses all of these into a single character.

Key characteristics include:

• Direct Attachment: It is placed immediately before the noun it modifies without any intervening particles (e.g., 其父 kei4 fu6 - 'his father'; 其妻 kei4 cai1 - 'his wife').
• No Particle (Standalone): You must never use 嘅 (ge3) with standalone 其, as the character itself already contains the possessive or demonstrative meaning. However, when 其 is part of a lexicalized compound word like 其他 (kei4 taa1) or 其中 (kei4 zung1), you can and often do use 嘅 (e.g., 其他嘅人 kei4 taa1 ge3 jan4).
• Not for Relative Clauses: Because 其 is inherently a pronoun, it cannot function as a structural linking particle. It cannot be used to connect adjectives or relative clauses to nouns (e.g., you cannot use it to replace 嘅 (ge3) in phrases like 靚嘅衫 leng3 ge3 saam1 or 我食嘅嘢 ngo5 sik6 ge3 je5).
• Not an Object Pronoun: 其 is never used as a direct object pronoun. You cannot say 'I saw 其' to mean 'I saw him/her/it'. In spoken Cantonese, use 佢 (keoi5), and in Classical Chinese, 之 (zi1) is used.
• Verb + 其 + Noun / Nominalized Phrase: A very common structure in idioms where 其 acts as the possessive modifier of the object of the verb, such as 順其自然 (seon6 kei4 zi6 jin4) ('let nature take its course'). It can also attach to verb phrases acting as nouns (nominalized clauses), acting as their subject, such as in 盡其所能 (zeon6 kei4 so2 nang4) ('do one's best / exhaust what one is able to do').
• Partitive and Enumerative: It is frequently used to list items or refer to parts of a whole, such as 其一 (kei4 jat1) ('number one / for one thing') and 其二 (kei4 ji6) ('number two').
• Register: As a standalone pronoun, it belongs to Standard Written Chinese (書面語) or Classical Chinese. Using it this way in casual conversation sounds overly formal.
• Common Compounds & Idioms: While the standalone use is formal, 其 is an essential part of daily spoken Cantonese in common compounds like 其他 (kei4 taa1) ('other'), 其餘 (kei4 jyu4) ('the rest / the remaining'), 其實 (kei4 sat6) ('actually'), 其中 (kei4 zung1) ('among them / in which'), 其次 (kei4 ci3) ('secondly / next'), 尤其 (jau4 kei4) ('especially'), 其間 (kei4 gaan1) ('during that time'), 其後 (kei4 hau6) ('afterwards'), 與其 (jyu5 kei4) ('rather than'), and idioms like 莫名其妙 (mok6 ming4 kei4 miu6) ('baffling / inexplicable').
• Modal/Adverbial Function (Classical): Disclaimer: While primarily a pronoun, in certain classical contexts or surviving idioms, 其 can also function as a modal adverb indicating a guess ('probably') or an imperative ('must/should'). This is important to note to prevent confusion when dissecting certain classical idioms.
• Colloquial Evolution: The very common colloquial term 求其 (kau4 kei4) ('casual', 'careless', or 'whatever') is fascinating. A well-known etymological theory suggests it derives from the Mencius quote '求其放心' (seeking its lost heart). It evolved through a linguistic mechanism called 'hiding words' (藏詞), where the last two characters ('放心') were dropped, leaving just '求其'. Crucially, a major etymological theory suggests that the colloquial Cantonese possessive particle 嘅 (ge3) actually evolved from the Classical Chinese 其 (or its variant 忌), providing a direct link between formal and spoken Cantonese. Furthermore, the spoken third-person pronoun 佢 (keoi5) is widely considered to be an etymological descendant or phonetic loan of the classical/Middle Chinese 其 (kei4) or 渠 (keoi4).