More notes about the รร ("run") vowel.

On its own รร is pronounced like the English word "run".

But it will never appear on its own.

1.     Normally it will be surrounded by two consonants, in which case it simply becomes the “puppy” vowel, as in ธรรม,pronounced ธัม (dharma) or กรรม, pronounced กัม (karma).

2.     Occasionally there will just be a consonant on the left and none on the right, in which case, the final “rolling ladyboy” becomes a kind of “n” at the “end”, as in บรร-ทุก (บัรทุก= truck)

3.     Conceivably, there could be a consonant on the right only and none on the left, in which case it would become ระ-, but I haven’t come across any words spelled this way.

This spelling is used in a few very common words, so unfortunately, one can’t just discard it as being too obscure:

รถ บรรทุก  truck
สุวรรณภูมิ  Suvarnabhumi (pronounced “su-wan-a-phoom” in Thai)
ธรรมดา  ordinary
ธรรมชาติ  nature/natural (the final "igloo" vowel isn't pronounced)
and
กิจกรรม  activity
บรรจุภัณฑ์  package
วัฒนธรรม  culture
พฤติกรรม  behavior