Colours in Thai: สี Plus One More Word

Every colour is สี plus one more word

สี on its own means colour, and Phayan's word list also glosses it as paint. Put it in front of another word and you get a colour name: สีแดง is red, สีเขียว is green, สีดำ is black. The pattern holds for every colour in the table below.

The second word names the colour without สี too: Wiktionary's first sense for แดง is red, for ดำ black and for ขาว white. สี in front makes it plain that a colour is meant, which matters for the words that have other senses. Read สี once and the second word is the only thing left to learn.

The thirteen colours, checked against the tone rules

The table was checked on 26 October 2026. Each consonant's class comes from the consonant table in Wikipedia's Thai script article, the tone in the dictionary column from each word's pronunciation on Wiktionary, and the last column from Phayan's own word list. Two-syllable words show both syllables.

Applied to the 13 colour words, the tone rules derive the tone Wiktionary gives for all 13, and none fail. One caveat: every syllable in the table is live, so the half of the rules that handles dead syllables never comes into play. Six of the thirteen, เหลือง, เขียว, น้ำเงิน, ชมพู, ม่วง and น้ำตาล, have no entry in Phayan's word list.

Several second words have other senses, and Wiktionary lists them. ส้ม is the fruit, an orange, and also means sour. ฟ้า is the sky. น้ำตาล is sugar. น้ำเงิน is น้ำ, water, plus เงิน, silver. Two that look like pure colour words are not: ดำ also means to dive, and แดง has a colloquial sense, to reveal. ม่วง was once the word for mango, and the colour is the colour of mango leaves.

Where each tone comes from

None of the tones in that table has to be memorised separately, and this is the part a romanised colour list cannot give you. A Thai syllable gets its tone from three things: the class of its first consonant, whether the syllable is live or dead, and any tone mark sitting above it. Four of the colours show the parts of the system the colours use.

• แดง is mid. ด is a mid-class consonant, the syllable ends in a sound that lets it ring on, and there is no tone mark. Mid class, live, no mark gives the mid tone every time.
• ขาว is rising. Same shape of syllable, but ข is high class, and high class plus live plus no mark gives rising. เขียว and เหลือง follow the same rule (เหลือง through its silent leading ห), which is why they are the three rising colours.
• ส้ม is falling. ส is high class and the syllable carries ไม้โท, the second tone mark. High class with ไม้โท is falling.
• ม่วง is falling too, by a different route. ม is low class and the mark is ไม้เอก, the first one. Low class with ไม้เอก also lands on falling, which is the sort of collision that makes the rules look arbitrary until you have the table.

The full version of that table is in the tone rules, and the consonant classes it depends on are set out in the three consonant classes. In Phayan the four tone marks arrive with the mid class in level 4, and the high and low classes follow in levels 5 to 7, so ส้ม and ม่วง become readable there.

สีฟ้า and สีน้ำเงิน are both blue

English calls both of these blue and leaves the rest to context. Thai uses two separate words. Wiktionary defines ฟ้า as sky and also as light blue or sky blue, and น้ำเงิน as dark blue. สีฟ้า is the pale blue of the sky; สีน้ำเงิน is the deep one.

น้ำเงิน is worth a second look for a different reason: it is น้ำ, water, plus เงิน, silver. Neither half is guessable from the meaning, but both halves are common words, so the spelling is readable long before the phrase makes sense.

สี and สี่ are one mark apart

สี, colour, is rising. สี่, four, is low. Wiktionary writes them /siː˩˩˦/ and /siː˨˩/. The only difference on the page is ไม้เอก, the small stroke above the vowel, and the official RTGS romanisation writes both as si, as Phayan's word list records. A learner working from English letters has to take each one from context; a learner reading the script sees the mark.

It is a small thing, and it is the whole argument for reading rather than transliterating, which is also why the numbers and the colours are worth learning in the same week.

Where colour words turn up

Each day of the week has a colour from Thai astrology, and the colour of the day you were born on is your birthday colour. That system, and the day names it hangs off, is in the days of the week.

สีอะไร, what colour, is the question to be able to ask and read first, since the answer comes back as one of the words above. Phayan's word list carries it as the example under สี.

How was this checked?

On 26 October 2026 a Python script using only the standard library read Wiktionary's pronunciation for the thirteen colour words and for สี and สี่, took each first consonant's class from Wikipedia's Thai script article, applied the tone rules to the spelling and compared the result with the dictionary. It also looked up each word in Phayan's own word list. The results are in dataset.csv, and check.py re-reads every page and runs the comparison again. The two other apps the FAQ names are described only from their own pages, read the same day: ThaiPod101's Colors list and Anki's home page.