乃

To Be (Classical Copula)

Level 6Sounds Like naai5

乃 (naai5) is a formal version of the verb 'to be'. While you use 係 (hai6) in 99% of daily life, 乃 appears in proverbs, legal documents, and historical dramas to sound authoritative or solemn.

How It Works

1. Register and Usage
乃 (naai5) belongs to the highest register of Cantonese. You will rarely hear it in a cafe, but you will see it in written laws or hear it in a graduation speech. It elevates the tone of a sentence from 'casual statement' to 'definitive truth.' In legal contexts, it is frequently used in definitions (e.g., 乃指 naai5 zi2, 'means/refers to').

2. Syntactic Structure
The structure is: Subject + 乃 + Noun Phrase.
Unlike 係 (hai6), 乃 (naai5) is rarely used with adjectives alone. It usually links two nouns or nominalized phrases. For example, in the proverb 'Failure is the mother of success,' both 'failure' and 'mother of success' are treated as nouns.

3. Common Pairings

  • 此乃 (ci2 naai5): 'This is...' (Formal). Used when presenting a gift or stating a fact in court.
  • Poetic/Archaic Pairing (乃係 naai5 hai6): A compound copula that combines the classical and modern forms. This is primarily found in literature, Wuxia novels, or religious texts rather than modern formal documents.
  • 乃...之...: Often appears with the literary possessive 之 (zi1) to maintain a consistent high register.

4. Distinction from Mandarin
While Mandarin also uses 乃 in literary contexts, in Cantonese, it is pronounced naai5 and is part of a specific 'High' register used by speakers to signal importance or historical weight.

Examples (5)

  1. 失敗乃成功之母。

    Failure is the mother of success.

    Word by Word: Failure is success 's mother.

    This is a famous proverb. 乃 (naai5) acts as the link between 'failure' and 'mother of success,' providing a timeless, authoritative tone.

  2. 此乃事實，不容置疑。

    This is a fact; it allows no room for doubt.

    Word by Word: This is fact, not allow place doubt.

    Used in a formal argument or legal setting. 此 (ci2) is the formal version of 'this,' matching the register of 乃 (naai5).

  3. 此乃我等之榮幸。

    This is our honor.

    Word by Word: This is we [plural] 's honor.

    A very formal expression of humility. To maintain register consistency, the literary possessive 之 (zi1) is used instead of the colloquial 嘅 (ge3).

  4. 彼乃何人？

    Who is that person?

    Word by Word: That is what person?

    Commonly heard in historical (Wuxia) dramas. 彼 (bei2) means 'that' and 何人 (ho4 jan4) means 'who' in classical style.

  5. 「董事」乃指公司之董事。

    'Director' means a director of the company.

    Word by Word: Director is refer company 's director.

    This demonstrates the specific legal usage of 乃 (naai5) in Hong Kong law to define terms (乃指 naai5 zi2).

Common Mistakes

  • Mixing 乃 with casual sentence-final particles.

    此乃事實囉。
    此乃事實。

    乃 (naai5) is highly formal. Pairing it with a casual particle like 囉 (lo1) creates a 'register clash' that sounds unnatural. Formal sentences usually end without particles or with formal ones like 也 (jaa5) in pure classical text.

  • Using 乃 to link a subject directly to an adjective.

    此乃好。
    此乃好事。

    Like most Chinese copulas, 乃 (naai5) needs to link to a noun phrase. To say 'This is good,' you must say 'This is a good thing' (此乃好事 ci2 naai5 hou2 si6).

  • Using 乃 in everyday conversation.

    我乃學生。
    我係學生。

    Unless you are acting in a play or being intentionally ironic, using 乃 (naai5) for simple identification like 'I am a student' sounds archaic and out of place.

How It Connects

Tap a pattern to see what it builds on and what it leads to.

乃Level 6To Be (Classical Copula)

Learn This First

乃 (naai5) is a classical copula used in place of the standard Cantonese 係 (hai6) to convey a sense of solemnity, formality, or to mimic archaic speech. Learners should already be familiar with the basic 'A is B' sentence structure in Cantonese and understand the distinction between spoken and formal written registers.

Words in This Pattern

乃