NaNoBotCo/thai-rtgs-romanisation-lexicon

Thai RTGS romanisation — the exception lexicon

694 Thai forms whose romanisation cannot be derived from the spelling, each with the reading a rule-based romaniser should use instead.

This is the companion to a rule engine, not a replacement for one. The rules handle the regular cases; this names the irregulars. Measured: it takes the romaniser behind motdang.net from 77.51% to 79.62% agreement on 153,948 Thai words, and from 83.45% to 84.22% on the 21,425 of them that appear in a place name — see the benchmark and the live romaniser.

Classes

class	entries	what it is
irregular	102	A dictionary word whose reading the letter rules cannot derive — chiefly Pali and Sanskrit forms whose written vowel is not said where it is written.
loanword	492	ทับศัพท์ — English written in Thai script. The reading IS the English word the spelling transcribes.
place	77	A place name in the spelling already on the road signs. RTGS cannot know where usage has fixed the word breaks: Mae Fah Luang, not Mae Fa Luang.
brand	23	A name's own Latin spelling, read off a record in the catalogue that carries it. A claim about spelling only.

Examples

Thai	reading	class
เกษตร	Kaset	irregular
เพชร	Phet	irregular
ถาวร	Thawon	irregular
มอเตอร์ไซค์	Motorcycle	loanword
คอมพิวเตอร์	Computer	loanword
เชียงใหม่	Chiang Mai	place
แม่ฟ้าหลวง	Mae Fah Luang	place
ปันนา	Punna	brand
ชมดอย	Chomdoi	brand

Why เกษตร is here

เกษตร is Sanskrit kṣetra. It is said ka-set; the letters say ke-set, and a syllable walker reading it left to right produces ketta. No rule derives this from the spelling, so it goes in a table. 739 records in the Mot Dang catalogue carried one of these forms; เพชรเกษม, a national highway, read "phetraketma" until it did not.

What is deliberately absent

Translations. กาแฟ → Coffee and เภสัช → Pharmacy are translations, and the readings Kafae and Phesat are correct — a translation does not belong in a romanisation table. Only pairs sharing a consonant shape were kept.

Fields

thai, roman, class.