Language: Burmese
Source: Period account
Da̱hmjaun (ဓားမြှောင်) is the name for a Burmese dagger.
In old colonial writings and among collectors today it is often spelled dha hmyuang.1
It consists of the words:
Da (ဓားမြှောင်); Knife, chopper, sword. And hmjaun (မြှောင်); 1. Be alongside; get alongside; stay alongside. 2. Depend on.

A fine Burmese dha hmyuang with carved ivory hilt.
Historical mentions
"I had neither knife, spoon, nor fork, so fingers had to do duty for all three, aided by a knife lent me by a Burman; these knives of theirs have a blade about six inches long, are very sharp, and are used alike for domestic purposes or for stabbing each other in a row." 1
-Colonel Fitz William Thomas Pollok, 1879
Notes to historical mentions
1. Colonel Fitz William Thomas Pollok; Sport in British Burmah, Assam, and the Cassyah and Jyntiah hills. Chapman and Hall, London. 1879. Volume 1. Page 54.
Other Burmese da types
Da (ဓား); Knife; chopper; sword; dah.
Da̱lwe (ဓားလွယ်); Sword in scabbard slung from the shoulder.
Da̱ma (ဓားမ); Chopper; knife with a broad blade.
Da̱mau (ဓားမောက်); Knife with a broad blade and curved point.
Hnge' kji daun (ငှက်ကြီးတောင်); A kind of long sword.
Lin gin (လင်းကင်); Machete-like sword with a crescent-shaped tip. A.k.a. "linkin dha".
Shan da (ရှမ်းဓား); Shan light sword with pointed blade.
Than lje (သန်လျက်); Double edged sword. Also: Four-edged dagger which forms part of the Myanmar regalia.2
Further reading
Glossary article: dha / da (ဓား).
Article: A Burmese da glossary
Sources
1. E.N. Bell I.C.S.; A Monograph on Iron and Steel Work in Burma. Rangoon, Superintendent, Government Printing Burma, 1907. Also see Robert Hales; Islamic and Oriental Arms and Armour: A Lifetime's Passion, England, 2013. Pages 148-149.
2. Terms taken from Adoniram Judson; Judson's Burmese-English dictionary, revised and enlarged by Robert C. Stevenson. Government Printing, Rangoon, Burma, 1893. Available on archive.org and Myanmar-English Dictionary by the Myanmar Language Commission. 1993. A useful online source is the SEAlang Library Burmese Dictionary Resources. All transcriptions are thus in the MLC Transcription System.