From Proto-Tai *boːᴮ. Compare Isan บ่อ, Lao ບໍ່ (bǭ), Lü ᦢᧁᧈ (ḃaw¹), Nong Zhuang mboq.
mbouj (Sawndip forms 否 or 冇 or 芪 or 布 or 保 or 𪜢 or 不, 1957–1982 spelling ƃouз)