One Invariant Verb Form across Person and Time | Thai Grammar

A Thai verb keeps one spoken and written form across person, number, and time. กิน means “eat” in ฉันกิน, เขากิน, เมื่อวานกิน, and พรุ่งนี้จะกิน. It never gains an ending corresponding to English eat/eats/ate/eaten/eating.

This does not make Thai vague or leave time unexpressed in everyday communication. Speakers locate events through time phrases, aspect and modal words, event order, and shared context. The verb itself stays unchanged while the surrounding clause does the grammatical work.

The verb does not agree with the subject

Compare one predicate across several subjects:

Subject	Verb	Object	Natural meaning
ฉัน	กิน	ข้าว	I eat rice/a meal
เขา	กิน	ข้าว	he/she eats rice/a meal
เราสองคน	กิน	ข้าว	the two of us eat rice/a meal
เด็ก ๆ	กิน	ข้าว	the children eat rice/a meal

ฉันกินข้าวที่บ้านค่ะ

chan kin khao thi ban kha

I eat at home. (ordinary polite speech, female speaker)

พี่ชายกินข้าวที่ทำงานครับ

phi chai kin khao thi tham ngan khrap

My older brother eats at work. (ordinary polite speech, male speaker)

เด็กสองคนนี้กินข้าวแล้วค่ะ

dek song khon ni kin khao laeo kha

These two children have eaten. (ordinary polite speech, female speaker)

The form กิน is identical in all three examples. Thai does not add an -s for a third-person subject, a plural ending for two children, or a past ending before แล้ว. Subject reference and aspect are separate from the verb root.

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Memorize one citation form for each Thai verb. Do not build a conjugation chart by person; build a construction chart showing what can appear before and after the unchanged verb.

Time comes from the clause, not a verb ending

A time phrase can locate an unchanged event directly. Thai often places a broad time frame near the beginning of the clause, though information structure can move it when context licenses.

เมื่อวานผมทำงานที่ร้านครับ

muea wan phom tham ngan thi ran khrap

Yesterday I worked at the shop. (ordinary polite speech, male speaker)

วันนี้ผมทำงานที่สำนักงานครับ

wan ni phom tham ngan thi samnakngan khrap

Today I am working at the office. (ordinary polite speech, male speaker)

พรุ่งนี้ผมจะทำงานที่บ้านครับ

phrung ni phom cha tham ngan thi ban khrap

Tomorrow I will work at home. (ordinary polite speech, male speaker)

ทำงาน stays unchanged. เมื่อวาน, วันนี้, and พรุ่งนี้ locate the event; จะ adds prospective or intended reference in the last sentence. จะ is common but not a compulsory future-tense ending: schedules and firmly established plans can be future through their time phrase and context alone.

The time-without-conjugation page develops how time adverbs, discourse, and aspect interact.

Aspect and modality surround the invariant verb

Thai distinguishes ongoing action, relevant completion, experience, expectation, and many other viewpoints with separate words. These are not alternative conjugated forms of the verb.

Pattern	Typical viewpoint	Example
กำลัง + verb	action in progress	กำลังกิน
verb + แล้ว	transition/completion now relevant	กินแล้ว
เคย + verb	prior experience	เคยกิน
จะ + verb	prospective, intention, prediction	จะกิน
อยาก + verb	desire	อยากกิน

ตอนนี้แม่กำลังทำอาหารอยู่ค่ะ

ton ni mae kamlang tham ahan yu kha

Mom is cooking now. (ordinary polite speech, female speaker)

ผมเคยกินร้านนี้หลายครั้งแล้วครับ

phom khoei kin ran ni lai khrang laeo khrap

I've eaten at this restaurant many times. (ordinary polite speech, male speaker)

เย็นนี้เราอยากลองร้านใหม่ค่ะ

yen ni rao yak long ran mai kha

This evening we'd like to try a new restaurant. (ordinary polite speech, female speaker)

Do not assign each marker one English tense. แล้ว can present a change of state, a completed event with present relevance, or discourse advancement. จะ can express intention, prediction, or a situation expected after another event. Their contribution depends on the complete construction.

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Translate the whole Thai clause, not one particle at a time. The same แล้ว may prompt English already, now, or a perfect form; that does not make แล้ว an inflection meaning “past.”

Negation precedes the predicate phrase

Plain ไม่ normally comes before the verb or predicate it negates: ไม่กิน “not eat,” ไม่ไป “not go.” Thai does not add English do/does/did and does not move the verb into a special negative form.

น้องไม่กินเผ็ดค่ะ

nong mai kin phet kha

My younger sibling doesn't eat spicy food. (ordinary polite speech, female speaker)

เมื่อวานผมไม่ได้ไปทำงานครับ

muea wan phom mai dai pai tham ngan khrap

I didn't go to work yesterday. (ordinary polite speech, male speaker)

เรายังไม่สั่งอาหารค่ะ ขอเวลาอีกนิดนะคะ

rao yang mai sang ahan kha kho wela ik nit na kha

We haven't ordered yet; please give us another moment. (polite restaurant speech, female speaker)

ไม่ได้ often denies that an event occurred or rejects an assumption; ยังไม่ means “not yet.” Both contain the same unchanged lexical verb after them. The ไม่ negation page treats scope and related negatives.

Arguments can be omitted when recoverable

Thai commonly omits subjects and objects that the conversation already identifies. The verb does not acquire agreement to compensate; listeners recover the participant from context.

กินข้าวหรือยังคะ

kin khao rue yang kha

Have you eaten yet? (polite question, female speaker; subject omitted)

กินแล้วครับ ขอบคุณครับ

kin laeo khrap khopkhun khrap

I have, thank you. (polite reply, male speaker; subject and object omitted)

The omitted subject changes from “you” in the question to “I” in the answer because turn-taking supplies it. This is discourse recoverability, not a hidden conjugation. If several people or foods are under discussion, overt reference may be needed. See argument omission.

Adjacent verbs do different jobs

Thai frequently places verbs next to one another: ไปซื้อกาแฟ “go buy coffee,” อยากกินข้าว “want to eat,” ลองอ่าน “try reading,” ทำเสร็จแล้ว “finish doing.” The second verb does not become an infinitive; Thai has no infinitive ending corresponding to English to.

เดี๋ยวผมไปซื้อกาแฟครับ

diao phom pai sue kafae khrap

I'll go buy coffee in a moment. (ordinary polite speech, male speaker)

ฉันอยากลองทำเมนูนี้ค่ะ

chan yak long tham menu ni kha

I'd like to try making this dish. (ordinary polite speech, female speaker)

Order reflects the conceptual relation: movement toward a purpose, desire before its content, or attempt before an action. Not every adjacent pair has the same structure, so do not insert English to mentally between every two verbs.

Ordinary-polite dialogue

วันนี้กลับบ้านกี่โมงคะ

wan ni klap ban ki mong kha

What time are you going home today? (polite question, female speaker; subject omitted)

กลับประมาณหกโมงครับ

klap praman hok mong khrap

Around six. (ordinary polite reply, male speaker; subject and destination omitted)

แล้วพรุ่งนี้เข้าบริษัทไหมคะ

laeo phrung ni khao borisat mai kha

And are you going into the office tomorrow? (polite follow-up, female speaker)

เข้าครับ มีประชุมตอนเช้า

khao khrap mi prachum ton chao

Yes; I have a meeting in the morning. (ordinary polite reply, male speaker)

The unchanged verbs กลับ and เข้า receive their time from วันนี้ and พรุ่งนี้. The dialogue also omits recoverable participants naturally.

Common Mistakes

1. Inventing third-person agreement

❌ เขากินส์ข้าวทุกเช้า

Incorrect—Thai does not add an English-style third-person ending.

✅ เขากินข้าวเช้าที่บ้านทุกวันครับ

khao kin khao chao thi ban thuk wan khrap

He eats breakfast at home every day. (ordinary polite speech, male speaker)

2. Treating แล้ว as a past ending

❌ เมื่อวานฉันแล้วทำงานที่บ้านค่ะ

Incorrect—แล้ว is not a past auxiliary placed before the verb; เมื่อวาน already supplies past time.

✅ เมื่อวานฉันทำงานที่บ้านค่ะ

muea wan chan tham ngan thi ban kha

Yesterday I worked at home. (ordinary polite speech, female speaker; simple past context without แล้ว)

3. Putting ไม่ after the verb

❌ ผมกินไม่เนื้อครับ

Incorrect for plain 'I don't eat meat'—ไม่ precedes the verb phrase.

✅ ผมไม่กินเนื้อครับ

phom mai kin nuea khrap

I don't eat meat. (ordinary polite speech, male speaker)

4. Adding an infinitive marker between verbs

❌ ฉันอยากถึงไปตลาดค่ะ

Incorrect calque—Thai does not insert a word meaning English infinitival 'to' here.

✅ ฉันอยากไปตลาดค่ะ

chan yak pai talat kha

I want to go to the market. (ordinary polite speech, female speaker)

5. Omitting an argument without enough context

❌ มาลีกินข้าวแล้วค่ะ แต่ยังไม่ได้กิน

Unclear—the second clause changes to another eater without identifying who has not eaten.

✅ มาลีกินข้าวแล้วค่ะ แต่เด็ก ๆ ยังไม่ได้กิน

mali kin khao laeo kha tae dek dek yang mai dai kin

Mali has eaten, but the children haven't yet. (ordinary polite speech, female speaker; overt contrast prevents ambiguity)

Key Takeaways

Thai verbs do not conjugate for person, number, or time. Keep the lexical verb unchanged and use arguments, time phrases, aspect or modal words, negation, order, and discourse context to build the intended meaning. Treat omitted participants and adjacent verbs as construction-specific choices, not evidence of hidden English endings or infinitives.

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