一定

Definitely

Level 2Sounds Like jat1 ding6

一定 (jat1 ding6) expresses strong conviction, certainty, or obligation, meaning 'definitely', 'certainly', or 'must'. It can modify verbs directly or combine with modal verbs like 會 (wui5, will) or 係 (hai6, to be) to make confident predictions or logical deductions (e.g. 一定係 jat1 ding6 hai6, 'must be').

How It Works

In Cantonese, 一定 (jat1 ding6) is the standard, neutral way to express absolute certainty or strong conviction, and can also function as an adjective meaning 'a certain amount' or 'a certain level'.

1. Word Order & Sentence-Initial Placement
In standard action sentences, 一定 follows the subject (e.g. 佢一定嚟 keoi5 jat1 ding6 lai4 = He is definitely coming). However, in logical deduction structures using 係 (hai6), 一定 frequently sits right at the start of the sentence: 一定係佢做嘅 (jat1 ding6 hai6 keoi5 zou6 ge3) = It must be him who did it.

2. Pairing with Modal Verbs
While 一定 can directly precede a verb, speakers frequently pair it with modal verbs like 會 (wui5, will) or 要 (jiu3, must) to clearly signal prediction or obligation:
• Prediction: 佢一定會嚟 (keoi5 jat1 ding6 wui5 lai4) = He will definitely come.
• Obligation: 你一定要做 (nei5 jat1 ding6 jiu3 zou6) = You must do it.

3. Asking Questions with '一定'
To ask if something is guaranteed or absolutely necessary, speakers frequently use the A-not-A question format 一唔一定 (jat1 m4 jat1 ding6) or the chunk 係咪 (hai6 mai6) before 一定. For example, 一唔一定要去？ (jat1 m4 jat1 ding6 jiu3 heoi3?) or 係咪一定要去？ (hai6 mai6 jat1 ding6 jiu3 heoi3?) both mean 'Must I go? / Is it absolutely necessary to go?'. Another example is 係咪一定得？ (hai6 mai6 jat1 ding6 dak1? = Is it guaranteed to work?).

4. Negation Scope & '冇一定'
The position of 唔 (m4, not) completely changes the meaning:
• 唔一定 (m4 jat1 ding6) = Not necessarily / not always.
• 一定唔 (jat1 ding6 m4) = Definitely not.
In spoken Cantonese, you will also frequently hear 冇一定 (mou5 jat1 ding6) as a standalone phrase meaning 'it depends' or 'nothing is set in stone'. It is also frequently used as a modifier meaning 'no fixed [noun]', such as 冇一定嘅標準 (mou5 jat1 ding6 ge3 biu1 zeon2 = no fixed standard).

5. Colloquial Equivalents: 實 and 肯定
In everyday speech, 實 (sat6) or 實會 (sat6 wui5) is a common informal substitute for 一定 (e.g. 佢實嚟 keoi5 sat6 lai4 = He's bound to come). Note that while 實 cannot be pre-negated to mean 'not necessarily' (because 唔實 m4 sat6 actually means 'loose' or 'not tight'), it can be followed by negation such as 唔 or 冇 (e.g. 佢實唔嚟 keoi5 sat6 m4 lai4 = He definitely won't come). Another common synonym is 肯定 (hang2 ding6), which functions similarly to 一定 as a marker of strong conviction (e.g. 佢肯定會嚟 keoi5 hang2 ding6 wui5 lai4 = He will definitely come). However, a core difference is that 肯定 can also function as a verb or adjective meaning 'to be sure' (e.g. 我唔肯定 ngo5 m4 hang2 ding6 = I am not sure), which is not possible with 一定.

6. Stylistic Note: Pairing with 㗎
Statements using 一定 or 實 are frequently capped with the sentence-final particle 㗎 (gaa3) to add an explanatory or reassuring tone (e.g. 佢一定會嚟㗎 keoi5 jat1 ding6 wui5 lai4 gaa3 = He will definitely come, don't worry).

7. Adjectival Usage
Beyond its adverbial use, 一定 can also function as an adjective meaning 'a certain amount' or 'a certain degree'. This is commonly structured as 一定嘅 + Noun, such as 有一定嘅水準 (jau5 jat1 ding6 ge3 seoi2 zeon2 = has a certain standard) or 遇到一定嘅困難 (jyu6 dou2 jat1 ding6 ge3 kwan3 naan4 = encountered a certain degree of difficulty).

Examples (5)

  1. 佢聽日一定會嚟。

    He will definitely come tomorrow.

    Word by Word: He tomorrow definitely will come.

    Combines 一定 (jat1 ding6) with the future modal verb 會 (wui5) to express high future prediction.

  2. 如果你想學好廣東話，你就一定要多啲聽廣東話。

    If you want to learn Cantonese well, you must listen to Cantonese more.

    Word by Word: If you want learn good Cantonese, you then definitely must more listen Cantonese.

    Combines 一定 (jat1 ding6) with 要 (jiu3) to express strict necessity or obligation.

  3. 貴嘅嘢唔一定係好嘢。

    Expensive things are not necessarily good things.

    Word by Word: Expensive possessive thing not definitely is good thing.

    Placing 唔 (m4) before 一定 creates 'not necessarily'.

  4. 佢一定唔會呃你，你放心啦。

    He definitely won't cheat you, don't worry.

    Word by Word: He definitely not will cheat you, you set-mind particle.

    Placing 一定 before 唔 creates absolute negative certainty ('definitely won't').

  5. 呢個計劃有一定嘅難度。

    This plan has a certain degree of difficulty.

    Word by Word: This classifier plan has certain possessive difficulty.

    Demonstrates 一定 (jat1 ding6) used as an adjective meaning 'a certain level' or 'a certain amount'.

Common Mistakes

  • Using 一定唔 when you mean 'not necessarily'.

    Different Meaning佢一定唔會去，但我都唔肯定。
    佢唔一定會去，但我都唔肯定。

    佢一定唔會去 is a fine sentence meaning 'he definitely will not go', which clashes with 但我都唔肯定. To say 'not necessarily', place 唔 before 一定 (唔一定).

  • Placing '唔' before '實' to mean 'not necessarily'.

    佢唔實會嚟。
    佢唔一定會嚟。

    You cannot place 唔 before 實 (*唔實) to express 'not necessarily'. While 實 can be followed by negation (實唔 / 實唔會 = 'definitely won't'), expressing 'not necessarily' requires 唔一定.

How It Connects

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一定Level 2Definitely

Learn This First

To use 一定 (definitely), you need to understand basic Cantonese word order, specifically that adverbs precede the verb. It is also helpful to know auxiliary verbs like 會 (will) because they are the most common partners for this pattern when expressing future certainty.

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