A wa (Thai: วา [wāː], also waa or wah, abbreviated ว.) is a unit of length, equal to 2 metres (2 m) or 4 sok (ศอก,) and is very nearly one fathom. Its current size is precisely derived from the metre, but is neither part of nor recognized by the modern metric system, the International System (SI). As a verb, wa means to outstretch (one's) arms to both sides.
The metre and derived units like kilometre are common in Thailand, but wa still occurs often as an alternative for tarangwa, 'square wa' (abbreviated ตร.ว. or ว๒,) a unit of area.
As for many terms normally written in Thai alphabet, transliteration into English language caused spelling variants waa and wah.